Columbus Tower / Sentinel Building (copper-clad flatiron)

The Columbus Tower, long known as the Sentinel Building, is a flatiron-shaped structure at the corner of Columbus Avenue and Kearny Street distinguished by its copper-clad facade, which has oxidized to the building's characteristic green color. The building survived the 1906 earthquake era and later became home to film company American Zoetrope, founded by Francis Ford Coppola, which occupies offices there. Its distinctive form and material make it a well-known architectural landmark in North Beach and the Telegraph Hill area.