Main Gate Park - Atlas Obscura

Main Gate Park

This building is a recreation of the gatehouse that separated Los Alamos from the outside world during the era of the Manhattan Project. 


Los Alamos, New Mexico, is a town that knows how to keep its secrets very well. Once a sleepy homestead and ranch school, today, Los Alamos is famous as “the Hill,” the secret compound that housed the scientists and military figures of the Manhattan Project. And through the war years, the only link between Los Alamos and the outside world was through the security gate whose replica stands today in Los Alamos Project Main Gate Park.

The security gate that stood outside Los Alamos is perhaps best associated with the woman who came to be known as “The Gatekeeper of Los Alamos,” Dorothy McKibbin. McKibbin, a civilian who moved to Santa Fe in the 1920s as part of her recovery from tuberculosis, was the primary contact for official workers and visitors who had to be brought to the Site. From her perch at 109 East Palace in Santa Fe, she would process people and issue temporary IDs for them to pass through the security gates. Official drivers would then make their way two hours through the mountains, delivering them to the gate.

The Main Gate was one of only two ways to access the outside world from Los Alamos, along with the less-used Back Gate that led to what is now Valles Caldera National Preserve. Even once a visitor made it to Los Alamos through 109 East Palace, entry was difficult. Visitor IDs were only valid for 24 hours, and visitors would be severely interrogated upon entry and searched for any identifying marks or scars. Passes would then have to be renewed every two weeks, and as author Jennet Conant notes, “Many an irate physicist and his tearful wife were detained at the gate, or turned away completely, because their passes had expired.”

In 2015, the Los Alamos Project Site was designated part of the Manhattan Project National Historical Park, along with the similarly hidden facilities in Oak Ridge, Tennessee, and Hanford, Washington. Soon after, Los Alamos Main Gate Park was built, and the gate that had once kept people from the secret facility was re-created. In 2021, interpretive signage was added, acknowledging the support of the Kiwanis Club of Los Alamos towards establishing and maintaining the park.

The sign is a little too neat, and the building too symmetrical, but the replica remains a terrific photo opportunity for visitors to the project site. Best of all, the gate now contains a hidden surprise of its own: a public restroom, for use by visitors. It’s a long way from a secret laboratory to a secret lavatory, but this park remains a destination for those who are looking to experience the history of this mysterious town.

Know Before You Go

Main Gate Park, and use of the restroom, is free and open to the public.

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