It was the first brownstone building west of the Mississippi River, and the only mansion on Nob Hill to structurally survive the 1906 San Francisco earthquake and fire.

[3][4] The Flood Mansion occupies an entire city block on Nob Hill, bounded by California, Cushman, Mason, and Sacramento streets.

It is a large masonry structure, three stories in height, its exterior finished in brownstone quarried in Portland, Connecticut and shipped around Cape Horn.

The main entrance, facing California Street, is sheltered by a broad and deep three-bay portico supported by clustered square columns.

His inspiration for the building was the Gilded Age mansions he saw on the East Coast of the United States, so he commissioned one from architect Augustus Laver.