Watchtower

When the Justice League was reformed by Wonder Woman, Superman and Batman, the Watchtower was built as the team's headquarters; an space-borne satellite, orbiting 22,300 miles above the Earth.

Linked with the Hall of Justice in Washington DC via an archway-type teleporation system, the satellite was designed by both Wonder Woman and Green Lantern (John Stewart), and paid for by Bruce Wayne.

In-Game History
Following the influx of heroes on Earth thanks to Future Lex Luthor's exobytes, the Watchtower was renovated to accomodate for the new recruits; creating individual wings that catered to either Meta, Magic or Tech based heroes.

Trivia

 * The Watchtower first appeared in JLA #7 (April 2007)