Commissioners' Court first met at Jacob Black's cabin on Feb. 26, 1836, before Fannin County was officially organized. In 1838 Warren (near present Ambrose in Grayson County) was named the county seat. The courthouse built there in 1840 was a two-story oak and cedar structure with rough plank floors. In 1843 the county seat was moved to Bois d'Arc; town's name was changed to Bonham, for an Alamo hero, the next year. Judge John P. Simpson donated land for the small log courthouse of 1843. Later another cabin was built with a breezeway connecting the two. In the early courthouse jurors sat above the courtroom in a loft that could be reached only by an outside ladder. (1974)
This log building served until 1881 when a two-story brick structure was erected at the same location. This was replaced in 1888 by a three-story courthouse made of native stone from Gober, south of Bonham, and built by Scottish-born stonemasons Kane and Cormack. Fire in 1929 destroyed the clock steeple, and the building was remodeled.
Using part of the 1888 structure, this courthouse was constructed in 1965-66 with a facade of Leuders stone. It was dedicated by Governor John Connally.