
Bancroft Tower stands atop Bancroft Hill in the city of Worcester, Massachusetts. A plaque set into the ground in front of it explains its purpose:

In case you can't read it, here's what it says:
BANCROFT TOWER THIS TOWER WAS BUILT IN 1900 TO HONOR THE MEMORY OF GEORGE BANCROFT 1800-1891 BORN AT THE FOOT OF THIS HILL HE ROSE TO THE POSTS OF SECRETARY OF THE NAVY FOUNDER OF THE U.S. NAVAL ACADEMY ANNAPOLIS, MARYLAND U.S. MINISTER TO GREAT BRITAIN AND GERMANY THIS MEMORIAL WAS BUILT BY HIS FRIEND AND ADMIRER STEPHEN SALISBURY III
Also notable about the small park in which the Tower stands are the two half-compasses set into the ground in front of and behind the Tower itself. They are marked as if they pointed to the other six of the Seven Hills of Worcester (Bancroft Hill itself being one of the seven), but it doesn't appear, from the top of the hill, that they really do. Nobody is sure what they're really pointing at, although some of my fringier friends claim they indicate the paths of the major ley lines which intersect at the Tower.

Bancroft Tower appears frequently in Eyrie Productions fanfics, since it's one of our favorite features of our old stamping grounds. It's a dimensional gateway in Hopelessly Lost, a place of significance in Neon Exodus Evangelion and the backdrop for Gryphon's "home stage" in Street Fighter: Warrior's Legacy.