Jefferson County Courthouse is a site on the National Register of Historic Places located in Boulder, Montana.

The architect selected to design the building was John Paulsen, a German immigrant.

The design was a two-story Richardsonian Romanesque style built with local granite and locally manufactured brick, with a square tower with an octagonal spire and two turrets.

Design elements drawn from the Middle Ages included gargoyles on each corner of the building, just under the eaves.

The interior of the building has extensive carved woodwork.