It is depicted as being located in the Manhattan of the Marvel Universe; it served as the replacement headquarters for the Fantastic Four when their original dwelling, the Baxter Building, was destroyed by Kristoff Vernard, the adoptive son of Doctor Doom.
The title of the building comes from a Franklin D. Roosevelt speech urging the Congress of the United States to enter World War II.
By the time of the original Baxter Building's destruction, Reed Richards, brilliant scientist and leader of the Fantastic Four, had already begun to realize that his increasing amount of inventions and equipment was taking up all of the team's available space.
[4] Reed, realizing the obvious inconvenience of a supervillain destroying your home, offered the tenants increased space under their old terms, including their 99-year leases.
[5] Subsequently, longtime Avengers foes the Masters of Evil (in the guise of the Thunderbolts, a new superhero team) took over residence of the building, and eventually destroyed it.
[6] Upon returning from the alternate reality with Franklin, the Fantastic Four were forced to move into their Manhattan warehouse along the Hudson River, nicknamed "Pier 4".