Between them is an open space linked by arcaded passageways and massive arched gateways to form the Plaza de California.

The city approved plans to divert vehicle traffic away from the Plaza de California and restore it as a pedestrian-only promenade, hoping to complete the project in time to celebrate the 2015 centennial of the exposition.

[4] However, the plan was challenged in court and was overturned by a judge on February 4, 2013, on the grounds that the city had not followed its own Municipal Code requirements in approving it.

The design and ornamentation combine many style elements including Gothic, Plateresque, Baroque, Churrigueresque, and Rococo to create the impression of a Spanish Colonial church.

The multi-tiered frontispiece is adorned with sculptures by the Piccirilli Brothers, a family of Italian marble carvers who also worked on famous monuments such as the Lincoln Memorial and the New York Public Library.

Attilio (1866-1945), the head of the studio, and Furio (1868-1949) modeled the historical figures and busts on the frontispiece of the California Building.

The great central dome is encircled with the inscription "Terram Frumenti Hordei, ac Vinarum, in qua Ficus et Malogranata et Oliveta Nascuntur, Terram Olei ac Mellis", (A land of wheat, and barley, and vines, and fig-trees, and pomegranates; a land of oil olive, and honey), (Deuteronomy 8:8 taken from the Vulgate of St. Jerome; see also the Seven Species), as well as the California motto, "Eureka".

[7] The building's facade features stone ornamentation as well as many historical figures and busts sculpted from modeling clay and plaster, depicting prominent people from California, England, Mexico, and Spain.

[8] During the Exposition the California Building was the home of the expo's theme exhibit, an anthropological display called "The Story of Man through the Ages."

[15] Just outside the California Quadrangle, on the west, is the first building visitors encounter as they cross the Cabrillo Bridge and enter El Prado Complex.

For many years after that the building was vacant, and the city proposed to tear it down in 1978, but it was eventually restored in the 1990s (sans ornamentation) and turned over to the Museum of Us.