Constructed primarily of Vermont-quarried Danby marble, the Amphitheater houses a small chapel underneath the stage. Judge Kimball, who died in 1916 before the construction was completed, is buried in Section 3 near the Amphitheater.
On October 15, 1915, President Woodrow Wilson placed the cornerstone, which contained the following items:
- The Bible
- The Declaration of Independence
- The Constitution of the United States
- A 1915 U.S. Flag
- The amphitheater designs and plans
- L'Enfant's map design of the city of Washington, D.C.
- An autograph of the amphitheater commission
- One of each of the U.S. coins in use in 1915
- One of each of the U.S. postage stamps in use in 1915
- A 1914 map of Washington, D.C.
- The Congressional Directory
- Boyd's City Directory for the District of Columbia
- An autographed photograph of President Woodrow Wilson
- The cornerstone dedication program
- The Evening Star newspaper account of the ceremonies, and the campaign to build the Amphitheater