The City That Hid Downward: Derinkuyu

Türkiye's Ministry of Culture and Tourism describes Derinkuyu as reaching a depth of about eighty-five metres and says that roughly a tenth of it can be visited. The district governorship of Derinkuyu, writing about the site beneath its own streets, says eight levels are open out of an estimated twelve or thirteen, reaching about fifty metres. The two bodies do not agree on how many floors there are, how much has been cleared, or even which year the place opened to the public. This is the most famous underground city in Cappadocia, and the official record cannot settle its basic dimensions — let alone who cut the first gallery.

Silence Index — D-004

Popular, with quiet hours

Ranks 79 of 99 scored dossiers — quieter than 20% of the others we have scored. A low score is not a warning; it describes who else will be standing next to you.

How the total is weighted. These are the fixed weights of the four inputs, the same on every dossier — not this place’s scores. We do not publish per-input bars, because the per-input values were never recorded article by article and inventing four plausible numbers that sum to the total would be a fabrication dressed as a chart.

Footfall pressure — visitors measured against the ground that absorbs them30%

Access friction — permits, caps, seasons, boats, weather windows30%

Acoustic floor — how close the nearest engine is20%

Unresolved questions — what the record still cannot settle20%

This dossier was scored before 2 September 2026, when the fourth input became night darkness. It keeps the input it was reasoned with until it is re-scored at its next source re-check; the methodology page records the change.

The index is a desk instrument scored by this publication, not a field measurement. How it is calculated, and where it fails.

The town of Derinkuyu sits on the open plain south of Nevşehir, in the middle of Anatolia, at the western edge of the Melendiz uplands and roughly thirty kilometres down the road toward Niğde. On the surface it is unremarkable: a grid of low buildings, a bus stop, a mosque, agricultural land running flat to the horizon. The interest is entirely below. The complex lies under the modern town, and the modern town takes its name from what is down there — derin kuyu, "deep well", after the shafts sunk sixty to seventy metres to reach water, of which the district administration counts fifty-two.

Derinkuyu is not a stray curiosity. It lies inside a World Heritage property. Göreme National Park and the Rock Sites of Cappadocia was inscribed by UNESCO in 1985 under four criteria — (i), (iii), (v) and (vii) — covering 9,883.81 hectares between Nevşehir, Ürgüp and Avanos, and the inscription explicitly names the underground cities of Kaymaklı and Derinkuyu among the components of the property. UNESCO's own summary frames the region as preserving "the fossilized image of a province of the Byzantine Empire between the 4th century and the arrival of the Seljuk Turks", which is a precise and rather careful sentence. It describes what survives. It does not claim to date the digging.

The Ministry's own description of the site is worth reading closely, because it is the most conservative account available. It gives an approximate depth of eighty-five metres. It lists stables, cellars, dining halls, churches and pressing floors where grapes were worked into wine or molasses. It describes hundreds of rooms linked by extensive galleries and complex tunnels. It identifies a ventilation shaft fifty-five metres deep, connected to the surface, that also served as a water well. And it states that only ten per cent of the underground city, which opened to the public in 1965, can be visited today.

The discovery story is one of the few things about Derinkuyu that has been independently checked. In 1963 a local man knocked through a wall during home renovations and found a tunnel behind it; the version usually told involves chickens vanishing into a gap in the masonry. Snopes examined the claim, rated it true, and traced it to BBC reporting — while noting, pointedly, that it could not find definitive records of the site's exact size. That caveat has aged well.

Because the second official account differs. The Derinkuyu district governorship states that eight levels have been cleaned and opened out of an estimated twelve or thirteen, that the accessible sections reach about fifty metres, and that of roughly four square kilometres of total extent about two and a half have been cleared. It dates the earliest settlement to the Proto-Hittite period around 3000 BC, notes Roman-period finds including a marble eagle, describes intensive Byzantine use, and gives 1967 as the year of opening. A 2016 paper in Procedia Engineering by Nývlt and colleagues, examining the site as a work of rock engineering, gives up to eighteen floors, a deepest floor at up to eighty-five metres, more than fifty ventilation shafts — and 1969 as the year it opened to visitors.

Three sources, three opening years, three counts of floors. None of them is lying. They are simply drawing on a body of information that was never systematically assembled.

The part that is genuinely unsettled

The most recent scholarly treatment of the Cappadocian underground sites is a 2026 Springer volume in the Advances in Karst Science series, Underground Shelters of Cappadocia, Turkey, by the speleologists Ali Yamaç and Ezgi Tok. It is the closest thing to a comprehensive inventory: 253 underground shelters identified in the region to date, catalogued and typologised, with fifty treated in detail. Yamaç has surveyed Derinkuyu directly at the request of the museum authorities. The book's working attribution is that these structures were cut by local populations between roughly the seventh and eleventh centuries AD as protection against Arab raids. And the survey chapter says, without hedging, that the date of first construction is a topic of contention across the literature.

That contention is not a marketing device. It is a structural problem with the evidence. Rock-cut architecture is subtractive: you remove material rather than adding it, so there is no foundation trench, no construction layer, no sequence of floors building upward for an excavator to read. Deposits found inside a chamber date the last people to use it, not the people who cut it. Chambers were re-cut, re-plastered, joined to one another and repurposed over centuries, and many are still used as cellars by the villages above.

Görkem Günay's 2024 survey of the field in Valonia: A Journal of Anatolian Pasts sets out the consequence plainly. Textual evidence for Cappadocia largely disappears after Late Antiquity. Without datable inscriptions, the intervals between carving phases cannot be established. What is left is comparison of style.

The chronology largely relies on the stylistic comparison of wall paintings, carved decoration, and architecture; none of them can provide firm results.

On the underground cities specifically, Günay describes them as complex multilevel settlements with winding corridors blocked by rolling stone doors, notes that they are traditionally associated with the Arab incursions of the seventh to ninth centuries, and states that although more than forty such sites are known, their dating and historical context "remain rather obscure". Günay's own reading — that they probably served various purposes year-round and were used as temporary shelters in periods of turmoil — is offered explicitly as interpretation rather than established fact.

Günay's article carries a second warning that is directly relevant. For most of the twentieth century, Cappadocia's rock-cut landscape was read as monastic: a wilderness of hermitages and cave monasteries. That reading, Günay argues, was a modern construction, traceable to eighteenth- and nineteenth-century travelogues and to early scholars who inferred monasticism from landscape aesthetics rather than from evidence. Systematic survey since the 1980s has replaced it with a picture of mixed secular and religious communities, including aristocratic residences and funerary complexes. Cappadocia has been confidently misread before, at scale, by professionals. That should temper anyone's certainty about the underground sites now.

Which brings us to the figure everyone repeats. Derinkuyu is said, almost universally, to have sheltered twenty thousand people. The number does appear in peer-reviewed technical literature: Nývlt and colleagues state a capacity for up to twenty thousand inhabitants. But it appears there as a received figure, carried into an engineering paper from the general literature. Neither the Ministry's own description of the site, nor the UNESCO documentation, nor the recent survey work offers a derivation — no floor area per person, no count of sleeping chambers, no method. It is best treated as an order-of-magnitude claim of long standing rather than an archaeological population estimate, and it should not be quoted as though someone counted.

The word "city" deserves the same scrutiny. The specialist literature does not use it. Yamaç and Tok call these structures underground shelters. The Ministry's own text describes them as places carved to provide secure refuge in the event of a threat or attack. Günay leans toward temporary shelter in periods of turmoil. That reading is consistent with what is actually down there: stables for livestock you would bring with you, storage rooms, presses, wells that cannot be reached or fouled from the surface, and passages deliberately made low and narrow to restrict an intruder's movement. It is much less consistent with a permanent subterranean population going about ordinary life. The honest description is a fortified refuge, repeatedly extended, occupied hard for short periods and lightly for long ones.

Nor is the regional picture closed. In 2013, construction workers demolishing houses in Nevşehir uncovered entrances to another underground complex beneath a Byzantine hilltop fortress. As National Geographic reported in 2015, the municipality halted the housing project and brought in archaeologists and geophysicists; geophysical measurements from Nevşehir University suggested the site might span some 460,000 square metres, with corridors possibly reaching 113 metres deep. Finds — grindstones, stone crosses, ceramics — indicated use from the Byzantine period through the Ottoman conquest. The museum director quoted at the time was careful to say the true extent was unknown. Even the Ministry's own count of underground settlements in the region is given as a range: its page for Özkonak describes Cappadocia as holding approximately 150 to 200 of them. Yamaç and Tok list 253. Nobody has a final number.

Why it looks like that

The reason any of this was possible is geological, and it is specific. Kazancı and Suludere, writing in the Geological Bulletin of Turkey in 2020, define Cappadocia by the distribution of its ignimbrites — the welded and unwelded pyroclastic sheets laid down by the Nevşehir and Acıgöl calderas and by the Erciyes and Hasandağı stratovolcanoes from the late Neogene into the Quaternary. They propose distinguishing a "Greater Cappadocia", meaning the full spread of that volcanic material, from a "Central Cappadocia" defined by its erosional signature: fairy chimneys, deep valleys and underground cities. The carved landscape is not incidental to the geology. It is one of the criteria by which geologists draw the region's boundary.

The layering matters as much as the material. Doğan and colleagues, in Mediterranean Geoscience Reviews in 2019, reconstruct the Melendiz river valley immediately south-east of Derinkuyu: a fluvial sequence with ignimbrite intercalations deposited through the late Miocene and early Pliocene, overlain by Pliocene lacustrine limestone, then incised. The Melendiz cut some 160 metres down through those sediments and the ignimbrites beneath them to create the Ihlara canyon. That is the same stack of soft sheets, tens of metres thick, that a person with an iron pick can work downward through.

The engineering properties are the other half of the answer. Nývlt and colleagues emphasise that the pyroclastic rock at Derinkuyu is self-supporting and needs no additional reinforcement, and that its hardness is not high. Those two facts together are the whole trick. Rock that is soft enough to cut with hand tools normally has to be propped; rock that stands unpropped is normally too hard to cut quickly. Cappadocian tuff does both, which is why the region has more excavated space than built space.

Softness has a cost, and it is being measured. Ömer Aydan and Reşat Ulusay published a geomechanical evaluation of Derinkuyu in Rock Mechanics and Rock Engineering in 2013, drawing on observational, experimental and theoretical rock-mechanics work carried out in the region since 1996. They installed acoustic emission and electrical potential monitoring systems on the fifth and seventh floors to track how the surrounding rock responds, and logged temperature, moisture and air pressure, in order to assess short- and long-term behaviour and model the stability of the complex. Their work examines the index and mechanical properties of the tuff and specifically the effects of water content and of freeze–thaw cycling. The same porosity that made the rock carvable makes it vulnerable to water and frost, and a site cut a thousand or more years ago is now a long-term stability problem as well as an archaeological one.

Ventilation is the feature visitors notice and the one most often exaggerated. What can be said from the technical literature is that Nývlt and colleagues record more than fifty ventilation shafts, arranged so that even the lowest and most remote parts of the complex are adequately ventilated, and that the Ministry identifies one fifty-five-metre shaft that served simultaneously as a well. It is worth noting that this was not a single standard design. The Ministry's description of Özkonak, forty-odd kilometres north, records a quite different solution: narrow openings connecting floors, and ventilation holes about five centimetres across that keep air moving when room entrances are sealed. These were separate communities solving the same problem in different ways.

AI illustration

How to actually see it

Derinkuyu is a Ministry of Culture and Tourism site, administered through the Nevşehir Museum Directorate, at Bayramlı Mah., Şemşili Yolu Sok. No. 15. The Ministry's listing gives daily opening from 08:00 with closing at 18:45 and the ticket office closing at the same hour, plus a listed evening slot from 19:00 to 21:00 with the ticket office closing at 20:15. Hours and the availability of the evening slot are revised periodically, and a General Directorate announcement was needed at one point to confirm weekend opening for foreign visitors at Derinkuyu and Özkonak — so confirm on muze.gov.tr rather than assuming. Tickets are sold at the gate and as e-tickets through the same site; the Ministry does not publish the entry price on the site's information page, and Turkish museum prices have been revised repeatedly, so check the current figure before budgeting.

The regional pass is worth considering only if you are moving fast. The Ministry's own store lists the Museum Pass Cappadocia e-card at €65, valid for three days from the first visit, covering more than ten Ministry museums and archaeological sites in Nevşehir province, with the Göreme Dark Church excluded and requiring a separate ticket. A Turkish-lira card version is listed separately at 320 TL. MüzeKart, the national card, is valid for Turkish citizens. The pass's site list is published as a separate document and does change; verify that Derinkuyu is on the current one before buying on that basis.

Getting there is genuinely easy, which is the site's problem as much as its convenience. Nevşehir Kapadokya (NAV) is closest; Kayseri (ASR) has more connections. Derinkuyu lies about thirty kilometres south of Nevşehir and is served by dolmuş from the Nevşehir bus station, or is a straightforward drive from Göreme, Ürgüp or Uçhisar.

Expect company. Anadolu Agency figures reported in 2024 put visits to the province's six ticketed underground cities at more than 1.49 million in 2023, with Kaymaklı alone taking around 560,000 and the district mayor publicly targeting a million for that site in 2024. The first hour after opening and the last hour before closing remain the two windows where the passages are quiet, and the evening slot, where offered, is quieter still.

The cheaper and quieter option is real. Özkonak, fourteen kilometres from Avanos on the northern slopes of Mount İdiş, is listed by the Ministry as open daily 08:00 to 20:00 and receives a small fraction of Kaymaklı's traffic; its inter-floor communication slots and five-centimetre ventilation holes are, technically, more interesting than anything at the larger sites. Kaymaklı, also listed 08:00 to 20:00, has four excavated floors and an andesite block with fifty-seven carved holes used for grinding and crushing. If you have one morning and a low tolerance for crowds, Özkonak is the better choice; if you want the site the literature actually argues about, it has to be Derinkuyu.

Practical constraints follow from the architecture. The passages were cut low, narrow and sloping to restrict an intruder's movement, and that design has not been softened for visitors. The complex is cool year-round and the steps are worn. Anyone strongly claustrophobic should decide at the entrance rather than partway down a single-file tunnel, because turning round against the flow is not straightforward. Operators commonly advise a torch and nothing bulky on the back.

Why the Silence Index is 54

The Index measures how much the world has to work to reach you here, and at Derinkuyu the answer is: almost not at all. Two airports serve the region. A public minibus runs from the provincial capital. You can buy the ticket online before you leave home, or at a window beside a car park. The site sits inside a mature tourism economy with a heritage pass designed to move visitors between its attractions efficiently. Provincial underground-city visits exceeded 1.49 million in a single recent year. On access friction alone the score belongs in the low fifties at best, and there is no argument to be made otherwise.

What holds it at 54 rather than dropping it into the thirties is the ratio of seen to unseen, and it is a genuinely striking ratio. By the Ministry's own account roughly ninety per cent of Derinkuyu is not open. By the district's account, four or five levels below the visitor route remain uncleaned. Regionally, 253 underground shelters have been catalogued and a handful are ticketed; the Ministry's own published estimate of how many exist is a range of fifty. A new complex of possibly comparable scale surfaced under a Nevşehir housing project barely a decade ago. And the central historical question — when the first gallery was cut, and by whom — is stated as unresolved in the current specialist literature rather than merely unclear in the popular one. A place can be crowded at eleven in the morning and still be, in every sense that matters, mostly unvisited. That is what a 54 describes: an easy, well-run public site attached to a very large volume of ground that nobody has walked and nobody can date.

Derinkuyu rewards a particular kind of attention. Not the awe of imagining twenty thousand people in the dark, which nobody has demonstrated, but the narrower and more durable interest of standing in a corridor cut by hand through volcanic ash by people whose names, century and intentions are all still open questions — in a country whose own authorities cannot yet agree on how deep the corridor goes. The site is well managed and honestly signposted. The problem it sits on top of has not been solved, and the people currently working on it say so.

The Traveler's Panel · checked 14 July 2026

Changing information. Prices, permits, seasons and road access change, sometimes at short notice. Everything here is a starting point for your own confirmation — not a quote, and not a guarantee. Verify with the operator and the relevant official body before you book.

Season	Year-round; Ministry hours revised periodically
Best hours	First hour after opening, last hour before closing, or the listed evening slot
Days needed	1.5–2 hours here; 3–4 days for Cappadocia
Difficulty	Easy underfoot, but low, narrow and sloping by design
Guide	Optional; useful for separating record from repetition
Cost band	$ — modest ticketed entry; regional pass only if moving fast

Getting there — Nevşehir Kapadokya (NAV) or Kayseri (ASR) → Nevşehir → Derinkuyu

1. Fly to Nevşehir Kapadokya (NAV), closest, or Kayseri (ASR), better connected.
2. Base in Göreme, Ürgüp or Uçhisar. Göreme is busiest and best served by transport.
3. Derinkuyu town lies roughly 30 km south of Nevşehir on the Niğde road; dolmuş run from the Nevşehir otogar, and it is a short drive from the Göreme–Ürgüp cluster.
4. The site address given by the Ministry is Bayramlı Mah., Şemşili Yolu Sok. No. 15, Derinkuyu, administered by the Nevşehir Museum Directorate.
5. Buy at the gate or as an e-ticket via muze.gov.tr. Confirm opening days and hours there before travelling — weekend and evening arrangements have changed by announcement in the past.
6. Go down the deepest open branch first while it is empty and work back up; most groups do the reverse.

Indicative costs — verify before booking

Derinkuyu entry	Not published on the Ministry's site page; check the current figure on muze.gov.tr before budgeting
Museum Pass Cappadocia	Listed by the Ministry store at €65 for the e-card, valid three days from first visit; a lira card version is listed at 320 TL
MüzeKart	Valid for Turkish citizens at Ministry sites including Derinkuyu
Licensed guide	Arranged locally; agree scope and price in writing before starting
Cave hotel	Wide band in Göreme, Ürgüp and Uçhisar; quieter towns are generally cheaper

What to pack

• A layer — the complex is cool year-round regardless of surface temperature
• Flat shoes with grip; the cut steps are worn and sloping
• A small torch for the side chambers the fixed lighting misses
• Nothing bulky on your back; the passages were cut narrow on purpose
• Water, and a plan if you are uncertain about enclosed spaces — decide at the entrance, not underground

Where to stay

Cappadocia's rock-cut hotels are genuine — many are converted historic dwellings in the same tuff as the underground sites — and they are the reason a large share of visitors come. Uçhisar and Ürgüp are quieter than Göreme and generally better value; Derinkuyu town itself has limited accommodation and most people visit as a half-day trip from the valleys to the north. If you book a room cut into rock, ask how it is ventilated and heated: the properties that make the stone comfortable in summer make damp a real management problem in winter.

Safety & responsible travel

• Do not touch or lean on the carved surfaces. The tuff is porous and soft — the same property that made it carvable makes it abrade, and published rock-mechanics work at the site is specifically concerned with moisture and freeze–thaw damage.
• Do not enter closed branches or step past barriers. About ninety per cent of the complex is not open to visitors, and stability monitoring is ongoing.
• Treat the churches as religious spaces, not photo backdrops.
• Use a licensed Turkish guide, and treat confident dates with suspicion. The current specialist literature describes the founding date as contested; anyone giving you a single unqualified century is going beyond the evidence.
• If crowding is spoiling the site for you, go to Özkonak instead. Spreading visitors across the region's lesser sites is the most useful thing an individual traveller can do here.

Nearby, and quieter

Kaymaklı — the nearest comparable underground city, four floors excavated, wider and shallower than Derinkuyu and by some margin the busiest, at around 560,000 visitors in 2023. Özkonak, near Avanos — far quieter, with a distinctly different ventilation and inter-floor design. The Ihlara canyon, cut 160 m into the ignimbrite by the Melendiz river and lined with rock-cut churches, for a long walk on the surface. And, on the Ministry's own estimate, somewhere between 150 and 200 further underground settlements in the region — 253 by the most recent speleological inventory — of which only a handful are ticketed.

Getting there, in order

• 1Nevşehir Kapadokya (NAV) or Kayseri (ASR)
• ↓
• 2Nevşehir
• ↓
• 3Derinkuyu

Each leg is a separate booking and a separate chance to be weathered out. Build spare days into the chain, not onto the end of it.

Where it is

Derinkuyu, Nevşehir, Türkiye · 38.3750°N 34.7350°E · Open in Google Maps · OpenStreetMap

Key locations

• Derinkuyu Underground City — the ticketed entrance under the modern town; about a tenth is open
  38.3736°N 34.7351°E
• Kaymaklı Underground City — the busier four-floor site, around 560,000 visits in 2023
  38.4603°N 34.7522°E
• Özkonak Underground City — the quiet alternative, with five-centimetre ventilation holes
  38.8131°N 34.8394°E
• Nevşehir — dolmuş departures, and the complex found under a housing project in 2013
  38.6250°N 34.7122°E
• Nevşehir Kapadokya Airport — nearest airport; Kayseri has more connections
  38.7717°N 34.5344°E
• Göreme — the usual accommodation base inside the World Heritage property
  38.6428°N 34.8286°E

Coordinates are for orientation and are accurate to roughly the width of the feature named, not to a doorway. Several of these points are inside protected areas or need a permit, a guide or a boat — read the access notes above before you plan a route to any of them.

Sources & further reading — checked 14 July 2026

1. UNESCO World Heritage Centre — Göreme National Park and the Rock Sites of Cappadocia. Inscription year, criteria and property area, and confirmation that Derinkuyu and Kaymaklı lie within the World Heritage property
2. T.C. Kültür ve Turizm Bakanlığı — Derinkuyu Yeraltı Şehri (official site listing). Official depth of c. 85 m, the statement that only ten per cent is open, the 55 m ventilation shaft doubling as a well, the 1965 opening date, address and published opening hours
3. T.C. Derinkuyu Kaymakamlığı — Tarihi Yeraltı Şehrimiz. The district administration's own and materially different figures — eight of an estimated twelve to thirteen levels, c. 50 m, 4 km² total extent, 52 wells, 1967 opening — used to document the disagreement between official sources
4. Ali Yamaç & Ezgi Tok, Underground Shelters of Cappadocia, Turkey, Advances in Karst Science, Springer (2026). Publication in May 2026; the attribution of these structures to local populations building between the 7th and 11th centuries AD against Arab raids; the framing of them as defensive shelters rather than cities; and the publisher's own summary that they number in excess of 200
5. Yamaç & Tok, chapter 3: 'Underground Shelters of Cappadocia'. The inventory figure of 253 underground shelters identified in the region to date; the typologies and standards; the techniques of subterranean excavation; the defensive devices and structural design; and the explicit statement that the date of first construction is a topic of contention
6. Görkem Günay, 'Byzantine Rock-Cut Architecture in Cappadocia and Beyond: The State of Scholarship', Valonia: A Journal of Anatolian Pasts 1 (2024), 35–63. The dating problem in rock-cut archaeology, the quoted line on stylistic chronology, the statement that more than forty underground sites are known but their dating and historical context remain rather obscure, and the dismantling of the earlier 'monastic myth' reading of Cappadocia
7. Ömer Aydan & Reşat Ulusay, 'Geomechanical Evaluation of Derinkuyu Antique Underground City and its Implications in Geoengineering', Rock Mechanics and Rock Engineering 46 (2013), 731–754. In-situ monitoring at Derinkuyu since 1996, including acoustic emission and electrical potential systems on the fifth and seventh floors, and the effects of water content and freeze–thaw on the tuff
8. V. Nývlt, J. Musílek, J. Čejka & O. Stopka, 'The Study of Derinkuyu Underground City in Cappadocia Located in Pyroclastic Rock Materials', Procedia Engineering (2016). Peer-reviewed engineering account of the self-supporting pyroclastic rock, the count of more than fifty ventilation shafts, the 18-floor and 85 m figures, and the only traceable technical appearance of the 20,000-inhabitant claim
9. Nizamettin Kazancı & Yaşar Suludere, 'Kapadokya'nın Litolojik Yapısı ve Sınırları, Türkiye', Geological Bulletin of Turkey 63(3) (2020). Definition of Cappadocia by ignimbrite distribution from the Nevşehir–Acıgöl calderas and the Erciyes and Hasandağı volcanoes, and the use of underground cities as a defining feature of central Cappadocia
10. U. Doğan, A. Koçyiğit & E. Yılmaz, 'Geomorphological evolutionary history of the Melendiz River Valley, Cappadocia, Turkey', Mediterranean Geoscience Reviews 1 (2019), 203–222. Late Miocene–early Pliocene ignimbrite stratigraphy immediately south-east of Derinkuyu and the 160 m incision that produced the Ihlara canyon
11. Elif Kahya Yıldırım, 'Evaluation of Underground Cities in Nevşehir and its Surroundings in Terms of Cultural Geography', Asia Minor Studies 13(1) (2025), 77–105. Field-based cultural geography of the five principal Nevşehir underground settlements and their regional distribution
12. T.C. Kültür ve Turizm Bakanlığı — Özkonak Yeraltı Şehri. Opening hours for the quieter alternative site, its distinct inter-floor and 5 cm ventilation design, and the Ministry's own estimate of 150–200 underground settlements in Cappadocia
13. T.C. Kültür ve Turizm Bakanlığı — Kaymaklı Yeraltı Şehri. Opening hours, the four excavated floors, and the andesite block with 57 carved holes, used for the comparison with Derinkuyu
14. T.C. Kültür ve Turizm Bakanlığı — Museum Pass Cappadocia (official store listing). Official price of €65 and validity of three days from the first museum visit. The list of covered sites is published as a separate document rather than on this page, so the pass's coverage has to be checked against that list before buying
15. National Geographic, 'Massive Underground City Found in Cappadocia Region of Turkey' (2015). The 2013–14 Nevşehir discovery, the geophysical extent and depth estimates from Nevşehir University, and the museum director's caution about the unknown true size
16. Daily Sabah / Anadolu Agency, 'Nearly 1.5M tourists visit Cappadocia's underground cities in 2023'. Visitor volumes for the province's ticketed underground cities, used to justify the Silence Index score
17. Snopes — 'Massive Underground City in Turkey Rediscovered During Home Renovations?'. Independent verification of the 1963 discovery account, rated True, and the explicit finding that no definitive record of the site's exact size could be located

Official and scientific bodies are the authority for safety, regulatory and scientific claims. Commercial operators are used only for practical detail such as tour length, meeting points and indicative pricing — never for a safety or scientific statement.