Air Force One is not a single plane. There are a number of planes that are outfitted the same way and they are housed at Andrews Air Force Base, Maryland. The second official presidential plane used, in 1945 was named the 'Sacred Cow', although presidents had used other special planes since 1933.
In March 2012, President Obama took the British Prime Minister David
Cameron to a basketball game in Ohio aboard Air Force One.
The planes are only designated as Air Force One when the president
is on board.
A VC-9C that was once used as Air Force One and Air Force Two (vice
president) went on auction sale in June with an opening bid of