Built in 1916 as Municipal Pier #2, Navy Pier was planned to serve as a cargo facility for lake freighters and to provide docking space for passenger excursion steamers.
However, with the onset of WWII, the Navy needed much more space for technical training. In August 1941, Navy Pier was closed to the public, and converted to a Navy training center designated to accommodate up to 10,000 service personnel. A large hangar-type building and a drill hall were built on 20 acres just west of the pier. Six days before the attack on Pearl Harbor, classes began for aviation machinist mates, metalsmiths, and diesel mechanics.
In mid-1946, with WWII over, the Navy returned the pier to the City of Chicago. In the four and one-half years under the Navy, over 60,000 servicemen from the U.S. and Allied nations trained at the pier.