The Avengers Mansion is a three-story townhouse located at 890 Fifth Avenue in Manhattan. Built in 1932 by industrialist Howard Stark as his Manhattan residence, the mansion was donated to the Avengers. Soon after their inception by his son Anthony Stark, who as Iron Man, was one of the Avengers' founding members. Over the years the mansion has been extensively remodeled to accommodate the Avengers' special needs. The most significant exterior change occurred about a year after the Avengers moved in when Thor and Iron Man pushed the mansion about 35 feet back from Fifth Avenue in order to give the structure the privacy afforded by a front yard. The belowground sub-structure, part of Howard Stark's original construction, was expanded by the Avengers to encompass the full limits of the block-wide property to a depth of feet. The belowground levels of the mansion contain the top-security headquarters and computer intelligence systems. While the aboveground levels contain living quarters and a main floor in which all public functions of the Avengers are conducted.

First appearance: AVENGERS #2.

THIRD FLOOR
The top floor of Avengers Mansion had long been the hangar and landing runway for the Avengers' supersonic Quinjet. Employing the principles of a naval aircraft carrier landing deck, the third floor uses a wire (which catches the arresting hook of a quinjet) and a series of pistol-coupled pulleys that gradually decelerate the craft over a 30-foot distance. The third floor also contained computerized navigation aids, radar, and communications. The hangar had storage room for four Quinjet, three on storage dollies, and one in launch position. With the recent rescinding of launch privileges within city limits, the third floor hangar has been in disuse. All of the Quinjets have been moved to Hydrobase. Various members have suggested converting the facilities to other uses, but as yet what to do with the vacant hangar has not been decided

SECOND FLOOR
Private quarters for any Avenger who requests them comprise the entire second floor of the mansion. Unlike the third floor which was completely gutted to make room for the hangar facility, the second floor closely resembled the original floor plan and architecture designed and constructed by Howard Stark. While many members of the Avengers maintain residences outside the mansion, many members over the years have lived at the mansion full-time during their term of active membership. When space was available, a member such as the Wasp, who had a residence elsewhere, could use one of the bedrooms as a Manhattan apartment. At only one time in Avengers history were all eight bedrooms occupied. Usually at least half of the rooms remain vacant. Since the Avengers' inception, there has always been at least one Avenger living full time at the mansion. The following Avengers are the only ones never to have resided at Avengers Mansion: Thor, Iron Man, Hulk, Black Widow, Moondragon, Hellcat, Ms. Marvel, Falcon, and Captain Marvel. Anthony Stark's quarters, used infrequently by the Avengers' benefactor and never as his alter ego Iron Man, are still reserved for Stark's exclusive use.

GROUNDS AND MAIN FLOOR
Avengers Mansion is surrounded on three sides by a twelve-foot high concrete and reinforced steel wall, with a steel fence along Fifth Avenue. The yard, doors, and windows all have numerous surveillance systems to ascertain the identities of all visitors and detainment devices to intercept unauthorized personnel. Visitors seeking entrance to the mansion are screened at the front gate. The garden and patio in the backyard have sufficient foliage to afford Avengers a fair degree of outdoor privacy. The main floor of the mansion contains no materials vital to the Avengers' security or functions and thus is occasionally opened to the public for press conferences and social functions. The Avengers' only dining facilities are on the main floor, as is the private library. The Avengers' butler Edwin Jarvis is the only person quartered on this floor

BASEMENT
Recreational, training, and medical facilities comprise the first sub-surface level of Avengers Mansion. A fully equipped gymnasium, an Olympic-size pool, sauna and steam bath are available to the membership, as is a game room featuring a billiards table, pinball machines, and video arcade games. The Combat Simulation Room is a heavily reinforced area in which various robotic devices simulating humanoid and mechanical attacks can be engaged for training purposes. The Combat Room is monitored and programmed by the mansion's main computer system. Also on this level are emergency medical facilities, once used by Dr. Donald Blake and Dr. Henry Pym. There is also a cryogenic storage area in which certain individuals (members or adversaries) suffering from degenerative aliments can be placed in suspended animation.

SUB-BASEMENT LEVEL ONE
Sub-Basement Level One contains the Avengers' high security Assembly Room where all operational meetings are held. The Assembly Room is the most secure place in the entire headquarters complex due to its massive reinforcements and vault like entrance passageway. The first subbasement houses the Avengers' computer system which contains all of their crime / forensic files, operational records, and world security data.

Until recently when the Avengers' governmental security clearances were revoked, the Avengers' computers had limited access to the national security data of the Pentagon's computer system, as well as a direct common database with S.H.I.E.L.D. Now the only outside agency with which the Avengers routinely trade information is the Fantastic Four, Inc. The mansion's power supply, a thermoelectric generator, along with its attendant back-up systems, are also housed on this floor, as is the Robotics / Electronics Fabrication Area once used by Dr. Henry Pym and Anthony Stark. This area is currently used by Dane Whitman (the Black Knight).

SUB-BASEMENT LEVEL TWO
Until recently, Sub-Basement Level Two had been primarily used for storage. Howard Stark built it for private weapons testing and storage, and constructed the robot named Arsenal there that would later menace the Avengers. The Avengers have a submarine pen with its own waterway to the East River, but with the adoption of the Quinjets as the major means of transit, the submarine system fell into disuse. In recent months, the submarine pen and waterway has been refurbished to create the UGABS (Underground Airbase Shuffle) system, a secret means of rapid transit to the Hydrobase nine miles off the coast of New York. The shuttle is easily accessible from the assembly Room above, as well as other parts of the Mansion.