What You Actually Need to Know Before You Start Digging Into These Sites
I spent three summers mapping abandoned defense facilities across the Midwest and East Coast before my partner pulled me off it. The paperwork alone is what kills people first. You don't need clearance to look at publicly available records, but you do need to understand where the legal line actually sits, because it moves depending on whether you're on federal land, state land, or private property that used to be a government lease. Most people skip that part and end up with a trespassing citation instead of photographs. The term Cold War Secret Nuclear Bunkers covers roughly two distinct categories of structures, and treating them the same is a mistake. The first group is the hardened command centers built for continuity of government—places like the Mount Weather Outdoor Assembly Area or the Cheyenne Mountain Complex, both still active in some capacity. The second is the distributed fallout shelters and emergency operations centers that were built at the county and state level starting around 1961, many of which were never properly decommissioned and just quietly abandoned. The research approach for each is completely different.
Researching Cold War Secret Nuclear Bunkers Using Public Records
Start with the Freedom of Information Act requests to FEMA and the Federal Emergency Management Agency's predecessor organizations. The National Archives also holds a lot of the State Emergency Preparation Commission files from the early 1960s. These documents list every shelter that received federal funding, along with their original capacity and intended use. I found over two hundred sites in a single state just by pulling the grant files from 1962 through 1965. The records are surprisingly complete because the original builders needed paper trails for congressional oversight. The tricky part is that many of these facilities changed hands multiple times. A county emergency operations center built in 1963 might have been sold to a private company in 1987, then leased back by the government for another decade. The property records at the county assessor's office will usually show the transaction history if you know what to ask for. Don't ask for information about a bunker. Ask for the property transfer history on a parcel that abuts a known emergency management facility. Property records are public. Bunker records are not always.
Field Reconnaissance and Safety Realities
The physical structures are often less impressive than the files suggest. A lot of the county-level shelters were built on the cheap with standard concrete block and a sheet metal roof buried under a few feet of dirt. They were designed to protect against blast overpressure for maybe thirty minutes, not to be habitable long-term. The ones that survived the best are usually the reinforced concrete structures built after 1965 when the standards tightened following the Partial Test Ban Treaty and the shift toward hardened missile silo construction. Natural atmosphere is the real killer in these spaces, not structural collapse. I found a shelter in southern Ohio in 2014 where the carbon dioxide levels inside the lower level measured over four percent on a portable meter I brought along. That is past the point where alertness degrades and into the territory where you get headaches and shortness of breath within twenty minutes. The ventilation systems in most abandoned bunkers had sealed themselves shut decades ago, either through rust or deliberate closure by whoever last maintained the building. Opening a sealed chamber without testing the air first is how people end up in hospital beds. Asbestos is nearly universal in structures built before 1975 that were never properly abated. The insulation on the ventilation ducts inside these facilities was almost always sprayed on with an asbestos-containing material. If you disturb that insulation while exploring, you are breathing it. I stopped using a standard respirator for this work and switched to a half-facepiece air-purifying respirator with P100 filters, but even that is only rated for particulate matter, not for any chemical residues that may have accumulated from stored equipment or earlier industrial use inside the facility.
Get the Full Details
Documentation and Photography Guidelines
Bring a DSLR or mirrorless camera with a wide-angle lens. Smartphones do not capture enough detail for the kind of documentation these sites require. The original signage, the layout of control panels, the type of ventilation equipment installed—these are the things that actually date a facility and connect it to a specific era of Cold War planning. I once identified a previously unlisted emergency operations center in rural Kentucky simply by photographing the serial number on a generator still sitting in its mounting bay. That serial number traced back to a 1964 Department of Defense procurement record that listed the exact building it was installed in. Keep a field notebook with you. Write down the time, weather conditions, and any access issues you encountered. The GPS coordinates of every site you visit should be recorded, but do not post those coordinates publicly. This is not about secrecy for its own sake. Abandoned defense facilities attract vandalism, and the ones that still have intact interior equipment tend to get stripped within months of their location becoming known online. The documentation is for your own research record, not for public distribution.
Legal Boundaries and Practical Workarounds
You can legally be on public land adjacent to many of these facilities. The restriction is usually on entering the structure itself, not on viewing it from a public right-of-way. I have documented dozens of sites this way without ever crossing onto restricted property. Some facilities have visible entrances from public roads that are technically on government land but not posted as restricted. The distinction matters in court and it matters even more when you are trying to avoid making yourself a target for local law enforcement who already get enough calls about trespassers in these areas. One edge case that came up more often than I expected involves underground facilities that have partial surface access through former industrial or municipal buildings. A water treatment plant in West Virginia had a basement level that connected directly to an abandoned civil defense shelter built underneath it in 1961. The shelter itself was technically still federal property, but the water plant had been sold to a private utility company in 1992. I contacted the utility company directly, explained what I was working on, and they gave me permission to access the lower level through their basement. This kind of workaround works because the current property owner has no incentive to keep an unused underground space sealed, and they often do not even know it exists anymore. Just be honest about what you are doing. False pretenses will get you banned from every similar facility in the state.
What Most People Get Wrong About These Facilities
The biggest misconception is that these bunkers were well-stocked with supplies and equipment. The reality is that most were barely furnished beyond what was required by the original design specifications. The Federal Civil Defense Administration had standard blueprints for shelter interiors, and those blueprints called for concrete benches, a radio receiver, and a water storage tank. That was it. Food supplies, medical kits, and specialized equipment were supposed to be provided at the state and local level, and the records show that most jurisdictions never actually provided them. The empty rooms you find when you explore these places are usually exactly what the original plans showed, not a stripped-down version of something that was once fully equipped. Another common error is assuming that all of these facilities have intact structural systems. Many of the underground entries were deliberately backfilled or sealed during the 1970s and 1980s as the threat assessment shifted and the maintenance budget disappeared. The sealant materials used at the time—usually tar-based compounds and rolled asphalt—degrade over twenty to thirty years. An entrance that looked solid in a 1978 inspection report may have a compromised ceiling by now. Do not climb into a void space above a sealed entrance without checking the overhead structure first. I saw a concrete slab crack along a previous repair line when someone leaned against it in a facility outside Pittsburgh. Nobody was hurt, but the hole it created into the cavity above was large enough to fall through.
Where to Find the Primary Source Documents
The Federal Depository Library Program maintains copies of the Federal Register from the Cold War era, and the registers contain the actual notices about shelter construction grants, facility design standards, and decommissioning orders. These are free to access at any designated depository library. The closest one to me is about forty miles away, and I went there three times in two years pulling microfilm reels. It takes patience, but the information you get from those documents is primary source material that no secondary website can replicate. The Eisenhower Library in Abilene, Kansas holds a significant collection of civil defense planning documents from the early 1960s. The Kennedy and Johnson libraries have related materials in their presidential records divisions. These are not open-access collections—you need to submit a research request and wait for processing—but the finding aids are available online and will tell you exactly which boxes contain the documents you need before you make the trip. The National Personnel Records Center also holds some of the military-affiliated shelter documentation, though their retention schedule means not everything survived. There is no single master list of every Cold War bunker that was built. The records are fragmented across multiple agencies that no longer exist in their original form, and the institutional memory has largely deteriorated. What exists is a patchwork of property records, procurement files, declassified planning documents, and the physical structures themselves. The work of piecing it together is tedious and mostly thankless, but the people who have been doing it for a long time tend to be the ones who notice when a newly discovered facility turns out to be something genuinely unusual rather than just another concrete room with a rusted generator in it.
