The fire forced the closure of First Street for several hours while firefighters from Benicia, Vallejo and other nearby cities fought the flames.
The fire was out after an hour but firefighters stayed to check for hot spots and hidden damage, according to the San Francisco Chronicle newspaper.
Nobody was injured, authorities said, and the cause of the blaze is under investigation.
Flames were first reported on the second floor of the building at around 1 p.m., the newspaper said, and quickly spread throughout the wooden structure at 333 First St.
“An offensive fire attack was performed and crews obtained a quick knock down of the fire while facing challenging conditions,” Benicia fire division chief K.C. Smith said in a written statement.
“The fire was brought under control in just over one hour,” the statement said.
The top floor houses offices, but the bottom floor includes well-known businesses such as Kinder’s barbecue at the corner of West D Street and others facing a rear courtyard.
All businesses in the building are believed to have suffered damage, if not from flames than from smoke or water that was needed to prevent the fire from spreading to other historic buildings nearby.
The building was a hotel when it was built near a wharf on East Fifth Street in the 1850s and continued to operate as a hotel after it was moved to First Street in 1856.
It became the Washington House Hotel in 1897 after operating as the Fairview Hotel and Revere Hotel.
The Washington House is said to have accommodated several legislators when Benicia was California’s state capital from 1853 to 1854.
California became a state in 1850.
