The Thomas County Courthouse, located at 300 N. Court in Colby, is the seat of government of Thomas County, Kansas. The courthouse was built from 1906 to 1907 and replaced the county's original courthouse. Architect James C. Holland designed the courthouse in the Richardsonian Romanesque style. The front of the courthouse has a five-story clock tower with a Seth Thomas clock; the main entrance to the building is located in a Syrian arch at the bottom of the tower. A projecting wing is located on each side of the tower; the wings each have three windows on every story and a hipped roof with a dormer.