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

Registration closed

October 18, 19 and 20

All tickets for the October tours are sold out. Planning for spring 2024 tours is underway; the tour dates and registration times will be posted as soon as they are available.



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.