Terminal 2 opened in 1954 as the main airport terminal. After a drastic rebuilding designed by Gensler, it replaced Rotunda A as SFO's international terminal in 1983 until it was closed for renovation after the current international terminal opened in 2000. The initial plan was to convert Terminal 2 for domestic travel and reopen it by fall 2001, but the loss of passenger traffic after the terrorist attacks of September 11, 2001 put those plans on hold. The upper levels continued to be used as office spaces and for the airport's medical clinic, and the control tower remained in use.