Manhattan Project Historical Marquee behind Fence Opt

Behind-the-Fence Tours

Manhattan Project National Historical Park Tours

Go behind the scenes of America’s atomic history with exclusive access to secure sites at Los Alamos National Laboratory.

Take a rare opportunity to go "behind the fence" at Los Alamos National Laboratory, where select guided tours offer access to secure areas not typically open to the public. These tours are offered twice a year with advance registration and limited capacity. The most up-to-date information about these tours will always appear on this page.

These unique, guided tours 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.

2025 Tour Dates

Each tour lasts approximately four hours, with two tours offered per day and a maximum of 30 participants per tour.

May 2025 Tours

  • May 13
  • May 14
  • May 15

October 2025 Tours

  • October 14
  • October 15
  • October 16

2026 tour dates will be posted here after they are determined.

Registration & Lottery Process

Due to high demand, space on tours is allocated via an online lottery system. Lottery registration typically takes place several months before each set of tours. This system ensures a fair process, providing everyone with an equal opportunity to participate while alleviating the stress and urgency typically associated with first-come, first-served registration.

Click here to access the registration portal for October tours. When the portal is open, from June 15 to June 28, you may register yourself and one guest for a chance to win tour tickets. Please note that entering the lottery does not guarantee a spot on a tour. Lottery results will be announced in early July. 

Visitor Eligibility & Requirements

Due to security protocols at Los Alamos National Laboratory, all visitors must meet strict eligibility criteria before confirming tour participation.

Participants must:

  • Be U.S. citizens with original documentation (birth certificate, passport, tribal ID, or other qualified document).
  • Be at least 18 years of age.
  • Be able to walk short distances, stand for 30 minutes, climb stairs, and traverse over uneven surfaces.
  • Wear sturdy footwear and long pants.
  • Not bring cell phones, cameras, Bluetooth devices, or any type of recording devices.
  • Comply with all additional requirements outlined during registration.

To learn more about the Manhattan Project and other historic sites in the Los Alamos area, visit our Plan Your Visit page.