Willis Polk was one of San Francisco's most influential architects, and the Bourn Mansion is among his finest residential commissions. The building's dark clinker brick facade gives it a brooding presence on Webster Street, where it faces the ornate Victorians and Edwardians of Pacific Heights like a stern headmaster surrounded by exuberant students. The Georgian Revival style was deliberately anachronistic -- a throwback to the restraint of the early American republic, chosen to signal taste rather than ostentation. The interior matched the exterior's quality, with fine woodwork and classical detailing.

Bourn's wealth came from the Empire Mine in Grass Valley, which operated from 1850 to 1956 and produced over 5.8 million ounces of gold. He inherited the mine from his father and ran it as president of the Empire Gold Mining Company. The San Francisco mansion was his city residence; Filoli, the 654-acre estate he built in Woodside between 1915 and 1917, was his country retreat. Between the Webster Street mansion and Filoli, Bourn created two of the finest residential properties in Northern California, each in a different register but both expressing the same preference for quality over display.

The Bourn Mansion sits on a block of Webster Street known for its architectural quality. It is a private residence and not open to the public, which preserves the privacy that Bourn himself valued. Among the ornate facades and painted surfaces of Pacific Heights, the mansion's dark brick exterior reads as an act of deliberate understatement -- wealth expressed through materials and proportion rather than color and ornament. It remains one of the finest residential buildings in San Francisco, quietly refusing to compete with its showier neighbors.