Four Freedoms Plaza was designed by Reed Richards, who is more popularly known as Mister Fantastic, the leader of the Fantastic Four. The building was constructed under Richards' supervision by the firm Damage Control and by workmen associated with the original law enforcement agency known as S.H.I.E.L.D..
Four Freedoms Plaza is a forty-five story office building surmounted by the four story headquarters of the Fantastic Four. Separating the two structures is a buffer zone of electrical and mechanical equipment which provides air-conditioning, power, and some other functions for the Fantastic Four headquarters. In cases of emergency, as, for example, if the Fantastic Four's headquarters should be under attack, security mechanisms within the buffer zone can seal the headquarters area off from the rest of the building.
The entire building is made of non-traditional construction materials. The building is "woven" from carbon aramid thread; hence, although the walls are relatively thin, they are extraordinarily resistant to damage. The windows are made of a carbon lattice which most closely resembles diamond. The quarter-inch thick windows are integrally woven into place and are not removable.
Access to the Fantastic Four's headquarters is gained from the first floor through elevators guarded by the doorman, Mr. O'Hoolihan, who performed the same function for the Fantastic Four at the Baxter Building. The Fantastic Four carry special devices in their belts that emit coded signals that open the elevator doors. Others seeking access to the Fantastic Four's headquarters must request permission for entry through O'Hoolihan from the Fantastic Four themselves. Visitors who are admitted take an elevator up to the reception room, which is attended by Roberta, a robot receptionist constructed to appear human above the waist.
The upper structure of the building is a self-sustaining, heavily armored unit, which contains both the Fantastic Four's headquarters and the individual members' living quarters. The upper structure makes extensive use of computers, guard robots, and other advanced devices to maintain security. All interior doors are air locks and are governed by a central housekeeping computer. This computer is part of Reed Richards' main computer complex. The upper structure contains several major state-of-the-art research laboratories in various fields of science for use by Dr. Richards. Among the most noteworthy technological devices housed in the laboratories are the mechanisms permitting entry into the Negative Zone and a duplicate of Doctor Doom’s time machine.
After a battle with Onslaught left the world without the majority of the heroes, including the Fantastic Four, Freedom Four Plaza was left unoccupied. Under the disguise of Citizen V, Baron Helmut Zemo convinced Franklin Richards, who now legally owned the building, that the Thunderbolts, actually the Masters of Evil in heroic disguises, needed a headquarters to work out of. Trying to do the right thing, Franklin allowed the Thunderbolts to move into the building. However, Zemo would expose the Thunderbolts to the world, which left it occupied for the Fantastic Four to move in once again.