These unique, guided tours will take participants behind the fence on Los Alamos National Laboratory property, at the historic Pajarito Site, current-day Technical Area 18. Visitors will see the Pond Cabin, which served as an office for Emilio Segrè’s Radioactivity Group studying plutonium; a battleship bunker used to protect equipment and staff during implosion design explosives testing; and the Slotin Building, site of Louis Slotin’s criticality accident.


March 29 and 30

October 18, 19 and 20

Planning for spring 2024 tours is underway; the tour dates and registration times will be posted as soon as they are available. If you’d like to get a heads up about when registration will open for our next public tours, click here to enter your email address.



These exclusive, guided tours are only offered twice a year; they complement the Trinity Site open house dates. Each tour lasts approximately 4 hours. There are 2 tours per day with a maximum of 25 people per tour.
Safety and security are vital at Los Alamos National Laboratory. Your eligibility to visit a national security site will be verified after you register.

To learn more about Manhattan Project history in the Los Alamos area, visit our Plan your visit page.



Tour participants:

  • Must be U.S. citizens with original documentation, including an original birth certificate, passport, tribal identification, or other qualified document;
  • Must be at least 18 years of age;
  • Must be able to walk short distances, stand for 30 minutes, climb stairs, and traverse over uneven surfaces;
  • Must wear sturdy footwear and long pants;
  • Are not allowed to bring cell phones, cameras, Bluetooth devices, or recording devices of any kind onto the site;
  • Must follow all other requirements listed in the registration process.