The Opera House is a wood-frame building built in 1873, attached roughly to the adjoining brick Gem Theater, a 1937 masonry cinema.

Aleck Brown built the theater in September 1873 and featured a performance of Pygmalion and Galatea for its opening night, with a cast of professional actors from San Francisco.

[6] The two-story rectangular building shows elements of the Greek Revival style with its shallow front pediment.

It originally featured a one-story porch across the width of the facade with a balustrade above, removed but now restored.

A shed-roofed addition to the rear is built into the hillside and houses the stage at the second-floor level.