Horizon Base
From Tardis Wiki, the free Doctor Who reference
Horizon Base was a secret moonbase built by the United States of America as part of Project Horizon in the 1960s. Anything non-terrestrial from Horizon Base was sent to the Laboratory in Washington DC. The Project Horizon mission was completed in July 1969.
The base was located in Mare Tranquillitatis and was just visible from the Soviet Union's secret Gagarin Base on other side of Plinius. (PROSE: Moon Blink)
It succeded Moonbase Eisenhower, a previous secret American moonbase that was destroyed in 1963. (AUDIO: 1963: The Space Race)
