A malting factory built by the Canada Malting Company on the shores of the Hudson. Its address was 1700 Riverside Dr., New York. Because of the financial crash of 29, it remained unfinished and abandoned. It was however purchased cheaply by Nelson Gardner, who also noted that the company's logo, CM, matched the initials of his costumed adventurer persona, "Captain Metropolis", and repurposed it as his living facility and headquarters. When he decided to found the Minutemen, customed adventurers were auditioned there, and then it became their base of operations.
When the Minutemen were disbanded, the Tower was abandoned. Only Hooded Justice remained there. After his death Gardner demolished the building to eliminate any traces of him.
The top part of the Tower was a regular looking building accessed through the street. The other side had an obsevatory with a telescope looking across the Hudson to the city. The structure descended along the rocky slopes that made the river's shores, and reached down the Hudson, on a small dock. There was also a boat that apparently was used only once by the Minutemen.
Areas withing the building included a conference room, with chairs made by specially ordered African wood, a war room where the Minutemen arranged their operations, some warehouses.
Considering the existence of a tank and a boat, the structure must have housed wide spaces used as hangars or garages, obviously the heroes' living quarters, and perhaps unused spaces.