Despite the 1907 finish , building work had begun before the San Francisco earthquake the previous year , but extensive damage to the building site , and the rest of the city , slowed down the construction considerably . For a relatively small building such as Sentinel Building , with the extensive workforce available in San Francisco at that time , taking more than a year to complete the building was slightly longer than would have been expected
San Francisco earthquake
1906 San Francisco earthquake
Columbus Tower (San Francisco)