The Hall of Justice was built in Washington, DC. when the Justice League of America was founded, but it was later destroyed and abandoned. Or at least that is what the public thinks. It's basement is actually used as a base for the JL.
A second Hall of Justice was built in New York City, next to the U.N. Building when the Justice League was reorganized under ARGUS and the U.N.
The current Hall of Justice is thought by the public to be the headquarters of the Justice League but is only a tourist trap, connected by Zeta Portals to the Watchtower, the true HQ of the JL. But the Hall is also used sometimes as a meeting place for the League and their associates.
The Hall of Justice is a training facility, a meeting hall, living quarters, crime lab, and whatever else the heroes want to use it for. Basically a sanctuary for any hero who needs one. Most of the Founders have little need for it, outside of official meetings, but heroes like Fire and Ice live there.
- Museum: Open to the public, with interactive exhibits, trophies, statues, and often has one to three Justice League members available for photographs and autographs for PR purposes.
- ARGUS Headquarters: Also located on the complex is the site of the International Headquarters of ARGUS. Though restricted from public access, most of ARGUS' HQ is actually in the sub-levels and aboard the Watchtower, accessible via a Zeta-Beam.
- Founder's Hall: Inside the Hall of Justice, this is where the Justice League holds their meetings. There's 7 seats for the Founders down at the bottom of this large auditorium, with the Trinity seated in the longer table in the middle: Superman in the middle, Wonder Woman on his right, Batman on his left. The Green Arrow and Black Canary seated to Batman's left. Flash and Martian Manhunter to Wonder Woman's right. The Founders' Meeting is held here annually on the 10th day of April and is when new members are permitted to enter the League by way of a 57% majority vote.
- Also Features:
- A Cafeteria
- Sleeping Quarters
- Crime Lab
- Holding Cells
- Locker Room
- Zeta Beam Tunnel
- Training Simulator
- Astronomy Lab
- Occult Library
- Meditation Chamber
- Multipurpose Lab
- Computer Lab/Network Room 
Trivia and Notes
- Amanda Waller has an office in the Watchtower, but she usually does not use it. Same with Maxwell Lord, both preferring to keep their offices in the actual ARGUS HQ.
- The Hall's staff is mostly run by ARGUS' Justice League Division.They do have some contract staff (cleaning, groundskeeping, and cafeteria workers).
- The Watchtower and the Hall of Justice complex are owned by ARGUS.
- Martian Manhunter spends a lot of his non-monitoring time at the Hall of Justice, actively mentoring his fellow Justice League members.
- Wonder Woman spends a lot of her downtime in the Hall of Justice (because officially "Wonder Woman" lives in the Hall of Justice).
- The Hall of Justice Zeta-Beam is the primary way heroes access the Watchtower.
- There are hidden Zeta-Beams in most major cities, but the Justice League doesn't just give out those locations to every member, only giving out that information on a need to know basis or once you've spent a few years as a full-time member; and even then, you're not really supposed to use those indiscriminately as they want to keep the locations as covert as possible so they generally only use them for emergencies or when they are in a "secure" location, like the Fortress of Solitude, the Quiver, STAR Labs, and Batcave-5.
- Yes. Martian Manhunter has a considerable stash of Chocos in the Basement of the Hall of Justice.