William R. Thorsen House
U.S. National Register of Historic Places
Berkeley Landmark No. 4
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Location	2307 Piedmont Ave, Berkeley, California
Coordinates	37°52′8.34″N 122°15′7.09″W / 37.8689833°N 122.2519694°W / 37.8689833; -122.2519694
Area	0.4 acres (0.16 ha)
Built	1909
Architect	Greene & Greene[2]
Architectural style	Ultimate bungalow, American Arts and Crafts Movement
NRHP reference No.	78000646[1]
BERKL No.	4
Significant dates
Added to NRHP	November 20, 1978[1]
Designated BERKL	December 15, 1975 [3]

The William R. Thorsen House, often referred to as the Thorsen House, is a historic residence in Berkeley, California. Built in 1909 for William and Caroline Thorsen, it is one of the last of four standing ultimate bungalows designed by Henry and Charles Greene of the renowned architectural firm Greene & Greene and the only one located in Northern California.^[4][5]

Since 1942, it has been home to the Sigma Phi Society of the Thorsen House (alternatively Thorsen or the Sigma Phi Society of California), which hosts communal dinners, organizes small concerts, and offers tours for other students and members of the public, welcoming thousands of visitors a year.^[6]

Thorsen can be toured throughout the week on an informal basis; one can simply knock on the door to visit.^[7]

History

Namesake

The Thorsen House is named after William Randolph Thorsen (1860-1942), a lumber baron from Michigan who retired to and purchased a lot in Berkeley, California. His wife, Caroline Canfield Thorsen (1858-1942), was the younger sister of Nellie Canfield Blacker, owner of the Robert R. Blacker House in Pasadena, California. The couple resided in the house following its construction and until their deaths in 1942.

Design

The house embodies the American Craftsman style of the Arts and Crafts Movement, a style Greene & Greene is known for incorporating in their projects (as is the case with Gamble House and Blacker House, both in Pasadena).

The entry hall is paneled in Burmese Teak while the living and dining rooms are paneled in Honduras Mahogany with ebony pegs covering the screws. The fireplace in the living room is encased in mauve tile from the Grueby Faience Company. The front door contains leaded art glass in the pattern of a gnarled grape vine, executed by Emil Lange, who also worked on the Gamble House. The Greenes were originally commissioned to make furniture for the dining room, but were later called back to make additional pieces.