English: Looking southwest at the entrance of the old Gallatin County High School, 404 W. Main Street, Bozeman, Montana. Designed by local architect Fred Willson (who built much of downtown Bozeman), the small eastern brick structure was was constructed in 1902. The brick structure was extended in 1907. In 1937, the high school was vastly expanded with an Art Deco building, which became the main school building. Both extensions were designed by Willson.

In 1956, Gallatin County High School became the Willson Junior High School when the city constructed Bozeman Senior High School on West Main (which still houses the school). After the then-new junior high, built on Eleventh Avenue north of the high school, was opened in the fall of 1966, the structure became Willson Middle School. The middle school closed in 1991, and the building was occupied by Bridger Alternative High School. In 2009, Bridger Alternative moved to a different building, and the Willson School (as the Art Deco structure is known) now houses administrative offices for the Bozeman Public Schools. The East School (as the original brick building is known) is no longer considered safe due to a lack of fire sprinklers and it does not meed modern earthquake codes; it has been used for storage since 2010.

The entire structure was listed on the National Register of Historic Places on January 22, 1988.