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.

2026 Tour Dates

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

May 2026 Tours

• May 5
• May 6
• May 7

October 2026 Tours

• October 13
• October 14
• October 15

Registration & Lottery Process: October 2026

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.

The lottery for spaces on October 2026 tours took place in June. The registration portal for the lottery was open from June 1 to June 12, and results were emailed to all entrants on June 16. Tours and corresponding lottery registration periods have not yet been scheduled for 2027. As soon as our 2027 tour schedule is determined, we will post relevant dates and registration information on this page.

Visitor Eligibility & Requirements

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

You must verify that you meet the following requirements:

• Must be a U.S. citizen 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 be willing to comply with all rules for participating in a tour, including: wearing long pants and sturdy footwear, and agreeing not to bring cell phones, cameras, Bluetooth devices, or recording devices of any kind onto the site. 

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

About the Lottery

Can anyone enter the lottery for behind-the-fence tours?

Only U.S. citizens who are at least 18 years old and do not work at Los Alamos National Laboratory can enter the lottery. 

Is there an entry fee?

No. These tours and the associated lottery registration system are free of charge. 

Can I select my preferred tour date when I enter the lottery?

No. The lottery only determines who is eligible to book spots on any of the six tour sessions associated with that season’s tour series. Choosing your specific tour session is a first-come, first-serve process for lottery winners only. 

Can I enter the lottery with a friend or in a group?

Your lottery ticket is individual and represents one spot only. If you win the lottery and go on to sign up for a tour, you will be able to add one guest to your reservation at the time of tour sign-up. 

How random is the lottery process?

Each lottery is randomized using a well-known commercial data randomizer, giving every applicant the same chance of getting a spot on a tour.

How do I find out the lottery results?

All applicants will receive an email announcing the lottery results and indicating whether they were successful or not. This email should arrive within two weeks of the lottery closing date. 

How do I secure my spot on a tour if I’m a winner?

Winning the lottery does NOT mean you are automatically registered for a Behind-the-Fence tour. If you are selected as a winner, make sure to review all the details outlined in the email and follow all additional steps to register for a specific tour session. 

I didn’t win the lottery. Can I put my name on a waiting list?

After selecting applicants for available tour slots, the randomizer will also generate a waiting list. We will contact individuals on the waiting list as needed to fill all available tour slots. Please note that security procedures at LANL require us to "lock" the final list of tour attendees two weeks before tours begin, and we will not be pulling new names from the waiting list after that time.

If I win the lottery but then realize that the available tour sessions don’t work with my schedule, can I sign up for the next series of tours instead? 

No. Each lottery is conducted separately and is associated with specific tour dates. 

If I registered for a previous lottery, will I automatically be entered into the next one as well?

No. Each lottery is conducted separately and is associated with specific tour dates.

Contact

Los Alamos National Laboratory Los Alamos, NM 87545 | mapr@lanl.gov | 505-667-MAPR