Battleship Bunker in Pajarito Canyon, where important implosion tests preceded the Trinity Test. Courtesy/LANL

By MARLENE WILDEN
Los Alamos Daily Post
marlene@ladailypost.com

At Los Alamos’s Pajarito Site, also known as Technical Area 18 (TA-18), a quiet but profound restoration effort is unfolding. Led by archaeologists, historians and architects from Los Alamos National Laboratory (LANL), this work goes beyond stabilizing concrete bunkers and experimental facilities from World War II. It’s part of a deeper mission to honor the full legacy of Manhattan Project National Historical Park landmarks.

Recently deemed eligible for the National Register of Historic Places, TA-18’s restoration is revealing layers of history that predate the atomic era. Once home to Ancestral Pueblo communities and 19th-century homesteaders, this secluded plateau holds centuries of human stories alongside its role in nuclear science. What was once off-limits and shrouded in secrecy is now slowly being uncovered for public understanding.

Twice a year, a limited number of visitors are granted rare access to the LANL-hosted “Behind-the-Fence” tour, which since 2018, has offered a firsthand look at places where physics was pushed to its limits. As the restoration progresses, structures and the land they rest on are being reexamined to reflect not just scientific breakthroughs but also the cultural heritage and the narratives that shaped them.

For preservationists J.T. Stark and Ali Livesay, the work to protect and interpret these sites is both urgent and deeply personal, as its significance surpasses the temporary construction standards of its time.

Ali Livesay, archaeologist, and J.T. Stark, historic buildings specialist, provide historical interpretation for visitors during the ‘Behind-the-Fence’ tour at TA-18 in Manhattan Project National Historical Park. Courtesy/LANL

“This all comes down to the belief that no matter what culture you come from, you have a shared history,” said J.T. Stark, historic buildings specialist for the Manhattan Project National Historical Park at LANL. “We’re not just maintaining buildings — we’re protecting portals to one of the most pivotal chapters in human history. And the clock is ticking. Most of these structures date back to the mid-1940s, and decades of weather, wear and neglect have taken a toll.”

The Five‑Year Plan

The park, created in 2015, follows a rolling five-year preservation plan. High-priority projects address both visitor safety and protection of employees who work at or near historic structures. Completed work includes the 2021 restoration of Battleship Bunker, while current efforts focus on Casa One, a Cold War-era building constructed in response to the 1946 Slotin accident.

The Slotin Building bears the name of physicist Louis Slotin, fatally exposed to radiation here. Courtesy/LANL

“Much of the Manhattan Project-era concrete was mixed using large, smooth river rock aggregate that would not be suitable for modern construction. And the triple-seal gypsum board they used wasn’t really meant for exterior siding, and it definitely wasn’t meant to last,” said Stark.“But it was what the military had — apparently in surplus — so they used it. We see a lot of that.”

“It’s actually a research topic a few of us plan to follow in the future – to explore the temporary nature of the buildings, the temporary nature of the workforce, and how that connects to human behavior and the kind of resourcefulness you still see around the lab,” Stark said.

Preservation is not just confined to TA-18’s buildings. Archaeological investigations have revealed details missing from official records. At Gun Site, where tests supported gun-assembled weapons such as Thin Man and Little Boy, crews unearthed pieces of paraffin wax that appear to have been used to measure neutron levels — tangible insight into research not previously documented.

“Finding it gave us a clue about work we didn’t know was happening there,” Stark said.

Not every significant site is accessible. Some are deep inside secure areas, and others, like Casa One, require funding and safety upgrades before they can be added to the public tour. In the meantime, Stark and his team lead occasional student visits there, hoping to make it ready for wider audiences.

Funding for the work comes from the U.S. Department of Energy, which owns the land and buildings, rather than from the National Park Service. While the Park Service lends interpretive expertise and national recognition, it does not provide financial support. Stark said Los Alamos has an advantage over the other two Manhattan Project park sites, Hanford in Washington and Oak Ridge in Tennessee, because LANL’s leadership has consistently recognized the value of preservation.

“Compared to Oak Ridge and Hanford, Los Alamos has really done a great job providing the resources we need,” Stark said. “That’s in spite of their mission not being the preservation of historic buildings or running a national park.”

Unearthing Lost Histories

Other discoveries come from closer to the site’s historic core. Livesay, an archaeologist with the laboratory, recently found ceramics near Pond Cabin, once home to ranch school founder Ashley Pond’s family.

The Pond Cabin hosted a group studying plutonium during the Manhattan Project. Courtesy/LANL

“Even though we’ve done some work there before, the more I walk around supporting tours, the more I find,” she said. “Archaeology adds another line of evidence to the historic record. Sometimes it’s the little things, like a child’s tea set spout, that bring human stories to life.”

Livesay’s role blends compliance with education. Federal laws such as the National Historic Preservation Act require surveys and assessments before any new construction effort. Her work also emphasizes cultural responsiveness, particularly with neighboring Pueblo communities.

Consultation with sovereign tribal nations is formalized in government-to-government processes, but it is also about relationships.

“We’re trying not to think of archaeological sites as discrete resources,” Livesay said. “For many Pueblo people, these are interconnected, living places. Building our awareness of that perspective and incorporating it where we can is important.”

For Livesay, the value of the work extends beyond academic history.

“Just because we’re looking at the past doesn’t mean it’s over,” she said. “Our identities are tied up with our history and heritage. For many Pueblo people, past, present and future are not linear. They’re cyclical. The work we do affects living people.”

On tours, Livesay often points out how the plateau’s natural fortifications have drawn people for centuries, from Ancestral Pueblo builders to wartime scientists.

“It’s about human thinking over time,” she said. “We keep being creative in the use of the land, but the purpose of using it as a barrier has remained consistent.”

Rare Access for the Public

Demand far outpaces supply for the Manhattan Project National Historical Park’s “Behind-the-Fence” tours. Only 180 visitors are admitted each year, chosen randomly via an online lottery that opens in late winter for spring tours and again in summer for fall. Each tour involves coordination across multiple departments — craftspeople, transportation crews and security — to make the visits possible.

As the park nears its 10th anniversary in November, the preservation team is already mapping out the next phase of its plan. Alongside safety and structural integrity, they hope to expand archaeological research, integrate more Indigenous perspectives and, where possible, make more of TA-18 accessible.

“We want people to feel something when they’re here,” Stark said. “You can’t get that from a video. Being here, behind the fence, is different. It’s real.”