Known informally as the Octagon Building, the redbrick octagonal building at 118 Cooper Street (at the corner of Front Street) in Santa Cruz, California was built in 1882, adjacent to the first (1866) County Court House, to serve as the County Hall of Records.

In 1894, a major fire destroyed most of the nearby buildings, including the adjacent courthouse, but the brick Octagon survived.

Many historic brick buildings at the nearby Pacific Garden Mall were damaged during the 1989 Loma Prieta earthquake, but again the Octagon survived.

[1][4] Still owned by Santa Cruz County and administered by Santa Cruz Museum of Art and History (MAH), for a number of years the Octagon was used as the Museum Store.

At the end of 2024, the building is used by two food vendors as an extension of the adjacent Abbot Square Marketplace.