Sprinkled throughout the back roads of America are the remains of Armageddon. Or what could have been Armageddon had the Cold War between the United States and the Soviet Union suddenly gone hot.

The ghosts of America's atomic arsenal, from development to deployment, are accessible if you know where to look: in Arizona and South Dakota, decommissioned nuclear missiles still aim skyward; in Nevada and New Mexico, the remains of nuclear testing still scar the desert; and in Tennessee and Washington state, the facilities that developed uranium and plutonium for America's nuclear bombs gather dust.

In the coming months, the National Park Service and the Department of Energy will establish the Manhattan Project National Historical Park — preserving once-secret sites at Los Alamos, Oak Ridge, and Hanford, where scientists raced to develop the world's first atomic bomb. Public tours at these sites are already ferociously popular, selling out within days. The Park Service aims to better facilitate access to these sites to meet increasing public interest.

Yet elsewhere in the US, the ruins of the Manhattan Project and the arms race that followed remain overlooked. In North Dakota, a pyramid-like anti-missile radar that was built to detect an incoming nuclear attack from the Soviet Union pokes through the prairie grass behind an open fence. In Arizona, a satellite calibration target that was used during the Cold War to help American satellites focus their lenses before spying on the Soviet Union sits covered in weeds near a Motel 6 parking lot. And in a suburban Chicago park, where visitors jog and bird watch, nuclear waste from the world's first reactor — developed by Italian physicist Enrico Fermi for the Manhattan Project in 1942 — sits buried beneath a sign that reads "Caution — Do Not Dig."

Collectively, these sites are a visible reminder of America's nuclear history — a time when the threat of doomsday was as much a part of the landscape as the national psyche.

All photos by Jim Lo Scalzo/European Pressphoto Agency

A decommissioned Titan II intercontinental ballistic missile sits in an underground silo at the Titan Missile Museum in Sahuarita, Arizona. During the Cold War, Titan II missiles, each armed with a nine-megaton nuclear warhead, were deployed to Arizona, Arkansas, and Kansas and were kept on continuous alert. This site preserves the last remaining Titan II missile and launch facility.

Two rocket fuel handler outfits, which were worn by propellant transfer system technicians, are seen at the Titan Missile Museum.

The dome of an abandoned Titan II intercontinental ballistic missile site is seen in the desert outside of Vail, Arizona.

A satellite calibration target, used during the Cold War to help America's Corona satellites focus their lenses before spying on the Soviet Union, gathers dust in the desert outside Casa Grande, Arizona. At one time there were 272 of these 60-foot-wide crosses scattered throughout southern Arizona.

The room that would have served as the House of Representatives in the event of a nuclear war is seen in a once-secret nuclear bunker built for members of Congress beneath the Greenbrier, a four-star resort near White Sulphur Springs, West Virginia.

The 25-ton blast door of a once-secret nuclear bunker built for members of Congress is seen beneath the Greenbrier. The 112,544-square-foot bomb shelter, completed during the Cold War in 1961, included enough beds and supplies to accommodate all 535 lawmakers, as well as one staffer each. There were also decontamination chambers, an intensive care unit and a communications briefing room, all surrounded by three to five feet of concrete.

Decontamination showers inside the nuclear bunker built for members of Congress located beneath the Greenbrier.

An 18-ton blast door that was once-hidden behind a moving panel is seen at the entrance to the once-secret Cold War nuclear bunker built for members of Congress beneath the Greenbrier.

The former cafeteria of the nuclear bunker built for members of Congress beneath the Greenbrier.

The footprint of the former K-25 building, which enriched uranium for America's nuclear weapons, is seen in Oak Ridge, Tennessee. Built in secret during the Manhattan Project, the U-shaped K-25 was once the largest building in the world under one roof. Twelve thousand employees worked inside. Uranium enriched at the plant was in the atomic bomb that the US dropped on Hiroshima, Japan. The Department of Energy completed a five-year-long demolition of the massive building in 2014.

Tourists are seen in a long-exposure image visiting the Trinity test site at the White Sands Missile Range, just outside San Antonio, New Mexico. On July 16, 1945, scientists working with the Manhattan Project detonated the world's first atomic bomb at this site. The Department of Defense allows the public to visit just two days a year.

A replica of "Fat Man," the atomic bomb that the US dropped on Nagasaki, Japan, in World War II sits on a flatbed trailer at the Trinity test site.

A warning sign is seen on a fence surrounding the Trinity test site.

Visitors to White Sands Missile Park check out a "Hound Dog," a supersonic Cold War missile that could be launched from a B-52 and carry a nuclear warhead, at the White Sands Missile Range in New Mexico. The park displays more than 50 missiles and rockets that were tested on the range.

A concrete marker at a site known as "Plot M," which is located in a public park in suburban Chicago, warns visitors that radioactive waste from the so-called Chicago Pile (the world's first nuclear reactor), as well as other nuclear experiments, is buried beneath the soil in Red Gate Woods. Developed by Italian physicist Enrico Fermi for the Manhattan Project in 1942, the Chicago Pile was originally constructed under a football stadium at the University of Chicago. The reactor was relocated to Red Gate Woods in 1943 and was later buried in this same park, at a spot known as "Site A."

The control room of the X-10 graphite reactor, the world's second reactor after the Chicago Pile, is seen at Oak Ridge National Laboratory in Oak Ridge, Tennessee. Built in secret during the Manhattan Project, the reactor supplied plutonium to nuclear scientists working at Los Alamos. The X-10 will become part of the soon-to-be-established Manhattan Project National Historical Park.

The loading face of the X-10 graphite reactor, the world's second reactor after the Chicago Pile, is seen through the window of the control room at Oak Ridge National Laboratory.

The Sedan Crater, formed by a 104-kiloton thermonuclear detonation in 1962, is a major draw for visitors hoping to land a spot on one of 12 annual tours of the Nevada National Security Site, 100 miles northwest of Las Vegas, Nevada. The nuclear blast that created Sedan displaced 12 million tons of earth, leaving behind a crater 320 feet deep.

The Mosler bank vault, constructed to determine the effects of nuclear weapons on civil structures, survived a 37-kiloton blast in 1957 at the Nevada National Security Site. After the explosion, workers removed the vault's door and discovered that the simulated currency inside was undamaged.

The so-called "Apple-2 House" is one of two homes that remain from Doomtown — a fake American community that included cars, furniture, and mannequins located 100 miles northwest of Las Vegas that was destroyed by an atomic bomb test in 1955 to determine the civil effects of an nuclear blast. This house was a little more than a mile from the 29-kiloton nuclear explosion.

Western wheatgrass has grown in and around the former launch site of a Minuteman intercontinental ballistic missile just outside Wall, South Dakota. All that remains of the launch facility, whose missile held a 1.2 megaton warhead, is a barbed wire fence around an empty field.

An unarmed Minutemen intercontinental ballistic missile is seen in its launch tube at the Delta-09 launch facility just outside Wall, South Dakota. After the launch site was deactivated in 1994, following the Strategic Arms Reduction Treaty signed by US President George H. W. Bush and Soviet leader Michael Gorbachev, the National Park Service turned the facility into the Minuteman Missile National Historic Site.

Tourists walk through a blast door at the Delta 01-Launch Control Facility just outside Wall, South Dakota.

One of two launch key turn slots is seen at the Delta 01-Launch Control Facility.

The assistant launch control officer's station at the Delta 01-Launch Control Facility.

The blast door of the November-33 launch facility, which once protected a Minuteman intercontinental ballistic missile and is now owned by the North Dakota Historic Society, is seen at dusk in Cooperstown, North Dakota. The missile was removed to comply with the terms of the Strategic Arms Reduction Treaty.

Weeds poke through the concrete surrounding the cell cover of a missile silo that once contained a Sprint thermonuclear missile near Hampden, North Dakota. Sprint anti-ballistic missiles, installed here as part of the Safeguard Program, were designed during the Cold War to intercept a preemptive attack on nearby Minuteman intercontinental ballistic missiles, which were scattered throughout the area. Yet the Safeguard Program was only operational for less than a year in the mid-1970s before the Defense Department, concerned about the program's cost and effectiveness, pulled the plug.

The remains of a pyramid-like anti-missile radar, part of the the Stanley R. Mickelsen Safeguard Complex, which was built during the Cold War to detect an incoming nuclear attack from the Soviet Union, is seen just outside Nekoma, North Dakota. The complex was completed in 1975 and was operational for less than a year before the Defense Department ended the Safeguard Program.

The radioactive core of the F Reactor on the Hanford Site, one of nine nuclear reactors built to make plutonium for nuclear weapons, now sits cocooned in concrete near the banks of the Columbia River in Hanford, Washington. It will be another 75 years before the core is safe enough for workers to dismantle it. Established near the end of World War II as part of the Manhattan Project, the Hanford Site is one of the the most toxic nuclear sites in the Western Hemisphere. The federal cleanup effort at the sprawling complex is expected to last until the year 2060 and cost American taxpayers $150 billion dollars.

The remains of Hanford High School, which will become part of the soon-to-be-established Manhattan Project National Historical Park, are seen on the Hanford Site. In 1943 the American government used eminent domain to acquire the massive tract of land that would become the Hanford Site, relocating 1,500 people from three small towns.

The world's first full-scale nuclear reactor, the historic B Reactor, is seen from the window of a bus tour of the Hanford Site. The B Reactor, which was built in secret in 1943-1944 and produced the plutonium used in the Fat Man bomb dropped over Nagasaki, Japan, will become part of the soon-to-be-established Manhattan Project National Historical Park.

Visitors look at the core of Hanford's historic B Reactor.

A pressure monitor panel is among some of the vintage switches and indicators inside the main control room of Hanford's historic B Reactor.

A Hanford worker is seen on a TV monitor in a level-B protective suit as he cleans the most hazardous room at the Hanford Site, the Plutonium Finishing Plant's Americium Recovery Facility, also known as the "McCluskey Room." The room is named after former Hanford worker Harold McCluskey, who was injured in 1976 when a vessel inside a glove box burst and exposed him, and the room, to radioactive material.

The radioactive core of the DR Reactor on the Hanford Site, one of nine nuclear reactors built to make plutonium for nuclear weapons that are now cocooned in concrete, is seen through a bus window in Hanford.