The Lincoln Memorial hid a secret room for over 100 years. It just opened to the public for the first time. The new $69 million museum has floor-to-ceiling glass walls. Visitors can walk past the columns holding up the memorial above. Lincoln's own signed Emancipation Proclamation and 13th Amendment are inside.
The Secret Room Under the Lincoln Memorial Is Now Open
For more than a century, millions of people climbed the marble steps of the Lincoln Memorial without ever knowing what sat beneath their feet. That changed this summer, when a hidden chamber the size of a small stadium finally opened its doors as a public museum.
A Room Nobody Was Supposed to See
The Lincoln Memorial opened in 1922, but the massive support structure underneath it, known as the undercroft, was sealed off from the start. Workers stumbled across the space again during a 1975 renovation. Park rangers ran a handful of flashlight tours through it in the 1980s, but asbestos concerns shut those down for good. For the next several decades, the undercroft sat dark, known mostly to maintenance crews and a few curious historians.
A $69 Million Rebuild
That changed with a $69 million restoration, funded through a public-private partnership between the National Park Service, the National Park Foundation, and private donors. Construction crews spent years threading a modern museum into the raw underbelly of the memorial without disturbing the 122 concrete columns that hold the entire structure up. Designers wrapped the space in floor-to-ceiling glass, using a custom heated glass system to keep the historic concrete from sweating and cracking.
What's Actually Inside
The new 15,000-square-foot museum walks visitors through how the memorial was built and what it has meant to the country since. A theater built into the space projects archival footage directly onto the original pillars, including Marian Anderson's 1939 concert on the memorial steps and the 1963 March on Washington, where Martin Luther King Jr. delivered his "I Have a Dream" speech.
The biggest draw, though, sits in a glass case near the center of the exhibit: an original, signed copy of the Emancipation Proclamation, one of only 27 known copies from an 1864 fundraising sale, displayed alongside an original signed copy of the 13th Amendment, one of just 15 that still exist. Both are on loan from Citadel founder Kenneth Griffin, who acquired them in 2025, and are scheduled to remain on display through June 2027.
How to See It
Admission to the undercroft museum is free, though visitors need a timed-entry ticket booked through Recreation.gov, which carries a $1 service fee. Tickets are released up to a month in advance, with same-day walk-up slots also available. The famous statue chamber and steps above stayed open to the public throughout the entire construction project.
Frequently Asked Questions
When did the Lincoln Memorial undercroft open to the public?
What is inside the Lincoln Memorial undercroft museum?
How much did the Lincoln Memorial undercroft renovation cost?
Do you need tickets to visit the Lincoln Memorial undercroft?
Why was the Lincoln Memorial undercroft closed for so long?
Verified Fact
Verified Jul 16, 2026
Source: WJLA / ABC7 WashingtonShow verification details
Verified 2026-07-16 (independent fact-verifier audit). Primary source: WJLA/ABC7 ($69M cost CONFIRMED verbatim - "cost upwards of $69 million"; 15,000 sq ft CONFIRMED - "15,000 square foot undercroft experience"; opening date CONFIRMED - "opens on June 25"; EP + 13th Amendment on display CONFIRMED). Cross-checked against Smithsonian Magazine (WebFetch, full text read) which independently confirms all four core numbers: $69M, 43,800 sq ft total undercroft, 15,000 sq ft museum, 122 concrete columns, June 25 2026 opening. Cross-checked PR Newswire NPF release + Bloomberg + Art Newspaper for the Griffin loan: EP is one of 27 surviving Lincoln-signed copies from the 1864 Great Central Fair (USSC fundraising fair) CONFIRMED; 13th Amendment is one of 15 known Lincoln-signed copies CONFIRMED; both acquired by Kenneth Griffin (Citadel founder) in 2025 for $18.1M CONFIRMED, on loan through June 2027 CONFIRMED. Civil Rights Theatre claim (Marian Anderson 1939 concert + MLK 1963 speech projected onto undercroft foundations/pillars) CONFIRMED via thehotelwashington.com (WebFetch, full text: "visitors will see video and photographic footage of the 1939 Marian Anderson concert...the 1963 March on Washington") - Smithsonian and Washingtonian only vaguely gesture at an immersive theater without naming the specific footage, so this detail is single-sourced to a travel-guide site; content matches two other independent search summaries verbatim, so confidence is high but noting the thinner sourcing. NUMERIC COHERENCE: verified this fact never uses the 43,800 sq ft TOTAL undercroft footprint figure from the companion fact lincoln-memorial-undercroft-cave-opens-2026 (created Jun 17 2026) - this fact only uses 15,000 sq ft (the exhibit portion), $69M, and 122 columns, none of which appear in the companion fact (which uses 43,800 sq ft, stalactites, 1914 graffiti). Confirmed zero overlapping specific figures between the two facts - the sequel angle (now-open + whats-inside vs opens-2026) holds. text=social_text-stripped-of-bold MATCH. social_text 332 chars (within 280-420 band). No invented precision, no reversed agency, no upgraded language found. Reversed-agency check: Lincoln personally signed the displayed EP/13th Amendment copies (not merely period copies) - CONFIRMED by Art Newspaper/Bloomberg, this is accurate, not upgraded. ENGINE: engine=2 correctly labeled - Lincoln Memorial is instantly recognizable and the secret-room-plus-founding-documents narrative IS the story, not a name-drop; kept beat_freshness=1 caution note re: SF buried-ships and Petra hidden-tomb scheduling as-is. One item surfaced but NOT a fact-accuracy issue: a separate, currently-developing controversy (City Cast DC / NBC Washington / New Republic, Jul 2026) reports NPS whistleblowers allege the display case has exceeded safe temperature (80F+) and a broken security sally-port endangering the loaned documents. This does not contradict any claim in the fact (which does not describe storage conditions) but is politically charged and could surface in comments - added to social_ai_notes so comment-responder does not overstate either the wholesome opening angle or take a side on the preservation controversy.