The U.S. Navy Annex was not an architecturally significant building.

Built in 1941, it was four stories tall, encompassed one million square feet, and was shaped liked a comb with eight fingers.

Its pedestrian appearance was matched by its alternative name – Federal Office Building 2.

It was intended to be temporary, but it lasted more than 70 years.

It was intended as a warehouse. In the same year it was built, the Annex was converted to office use and eventually provided space for 6,000 workers, including U.S. Navy Women Accepted for Volunteer Emergency Service – WAVES.

The building was almost immediately adopted by the U.S. Marine Corps as its headquarters and rear command post for operations throughout the Pacific.

The Commandant of the Marine Corps was the only Department of Defense Service Chief who did not has his office at the Pentagon during World War II.

The building served as Marine headquarters through 1996.

The Annex replaced the Main Navy and Munitions Buildings which had been built on the National Mall between the Lincoln Memorial and the Washington Monument during World War I. Those buildings were also intended to be temporary and be demolished shortly after the end of that war. The buildings were finally demolished under the Nixon Administration in 1970.

The Pentagon, next door to the Annex, was started at about the same time to house the War Department. Construction began on Sept. 11, 1941, and the building was officially opened on Jan. 14, 1943.

When the Navy Command Center at the Pentagon was destroyed on Sept. 11, 2001, the center was relocated to the Navy Annex.

One of the eight wings of the building was torn down in 2004 to create space for the U.S. Air Force Memorial.

The rest of the Annex was demolished in 2013 and the property was added to Arlington National Cemetery.