Lake County Courthouse is of brick, kilned at Lakeport and coated with concrete. It was designed by A. P. Pettit in the Italianate architectural style.

The Courthouse withstood the disastrous earthquake of 18 April 1906 while other buildings in the vicinity were damaged in various degrees.

The building served as the seat of county government until 1968, when a new courthouse complex was built directly behind it.

Adapted from the NRHP nomination dated 28 October 1970.

Lake County Courthouse is also California Landmark 897.