The Watchtower

The Watchtower is an orbiting satellite, and the true headquarters of the Justice League. League members are transported to the Watchtower from the Hall of Justice and the Cave. The Watchtower has sensors that can detect immense energy surges on the surface of the planet, but does not have any weapons systems.

Early history
The League started operating out of the Watchtower after their base in Mount Justice was compromised. Its existence has been kept from public knowledge,

2010
The Justice League convened a meeting to discuss the possibility of admitting additional members to the League.

After being enslaved by the Light's mind control, the Justice League welcomed Vandal Savage aboard the Watchtower with a silent kneel of obedience. As Vandal gloated, Red Arrow slipped away in the Zeta-tube.

With the Light still in control of the Justice League, the Team had to infiltrate the satellite via another way. They used the Bio-Ship, and via a makeshift dock, entered. With the help of cure-tech, they negated the effects of the Starro-tech.

The Team celebrated the new year aboard the Watchtower and discussed the past events with the League.

2015
Martian Manhunter and Red Tornado monitored the disappearance of several heroes, and held a conference with Mal Duncan and Nightwing about it.

2016
In the Watchtower, John Stewart explained about Lobo and the Kroloteans. Adam Strange explained about Rann and showed a tech which traces Kroloteans. Nightwing decided that the team went after the remaining Kroloteans and investigate on Rann.

Captain Atom, Black Lightning, Doctor Fate and Zatanna watched the activation of the Zeta-Shield from the Watchtower's observation deck.

Captain Atom and Aquaman discussed the Reach's presence on Earth with Nightwing over a video connection.

Background in other media

 * The first JLA base to use the name "Watchtower" was built on the moon's surface during the Grant Morrison run of the JLA series. Earlier bases in Earth's orbit were called the Justice League Satellite; they returned to a satellite after Infinite Crisis.
 * This marks the fifth animiated appearance of the Watchtower. In the DC Animated Universe, there were two: one in Justice League (which was destroyed in the finale) and a new model in Justice League Unlimited. It also appeared in The Batman, Justice League: Crisis on Two Earths and Batman: The Brave and the Bold