When the Avengers first formed, industrialist Tony Stark (secretly Iron Man) provided the team’s original and most enduring base of operations: Avengers Mansion, a Fifth Avenue townhouse in Manhattan. Though the team occasionally utilized other locations, such as the West Coast Avengers Compound or the floating Hydro base (a.k.a. Avengers Island), the Mansion remained their true home, the heart of the team-a heart which was ripped out when an inane Scarlet Witch’s reality-warping powers slew several Avengers and wrecked the Mansion. Tony Stark’s weakened finances meant he could not afford to rebuild it or finance the team, and so the ruined Mansion was left derelict, a memorial to those who had fallen.
Several months later, a new team of Avengers formed. Despite his depleted fortune, Stark managed to supply this new group with a headquarters. Recently completed, Stark Tower is a skyscraper located in the heart of Manhattan, in the vicinity of Columbus Circle, some ten blocks away from the Fantastic Four’s Baxter Building. Though the Tower itself cost around $600 million to build, the land on which it stands was suspiciously cheap considering its prime location. Tony Stark had originally intended to rent out the ninety lower floors as office space, while using the top three levels as his new, state-of-the-art bachelor pad; however after four years of construction resulted in a striking 1138-foot tall structure which dominated the skyline, Stark found most prospective tenants reluctant to rent for fear that his Avengers ties would lead to attacks by “space aliens”. Since the Avengers needed, Stark decided not to fight these expectations; he determined the Tower would be used by the kind of people who would expect just such an attack. Stark gifted the top three floors to the new Avengers as their home, where members could meet, plan and, if need be, reside. The Tower was later revealed to be the location of the Sentry's hidden Watchtower and the two buildings have now effectively merged into a single unit. (The revelation of the Watchtower also forced the new Avengers team to go public.)
Featuring numerous high-tech security, surveillance, and training devices, Stark Tower is fully equipped to serve the needs of the world's most prominent super-hero team. The tower, in keeping with it's original purpose as a residence for a free-wheeling billionaire, also has a number of amenities for those living there, and serves as home for Stark, his butler Jarvis, and (until recently) Spider-Man, May Parker, and Mary Jane Watson-Parker.