Brittan Party House, Victorian residence in San Carlos, United States.

The Brittan Party House is a two-and-a-half-story redwood-framed building with an octagonal folly, steep gables, and an octagonal windowed cupola. Its shiplap exterior siding runs in multiple directions. It is one of the few remaining examples of nineteenth-century Octagon Mode buildings in the San Francisco Bay Area.

Nathaniel Jones Brittan, who co-founded the Bohemian Club of San Francisco in 1872 and later served as its president, built the house that year to entertain his fellow club members and to use as a hunting lodge. He had inherited about a third of his father John Wesley Brittan's Brittan Ranch, land bought from the Rancho de las Pulgas. The building was listed on the National Register of Historic Places in 1994.

Nathaniel Brittan co-founded the Bohemian Club of San Francisco in 1872 and was its president by 1892; he built the house to entertain club friends. The Brittan Manor House, his former residence of 1888, stands about half a block away at 40 Pine Avenue.

The property is located on Dale Avenue in San Carlos and is visible from the street, though interior access may be limited for visitors. Plan a daytime visit to view the architectural details and surroundings from different angles around the structure.

The building is one of only a handful of remaining Octagon Mode structures left in the San Francisco Bay Area. This unusual architectural movement of the 1800s enjoyed brief popularity, but most houses built in this style were demolished or substantially altered over time.