Hillsboro is the county seat of Hill County, laid out in September 1853 following creation of the county in May, 1853. The county was carved from the western part of Navarro County and was named for Dr. George W. Hill, early settler in Navarro who served as Secretary of War in the Republic of Texas and who represented Navarro County in the State Senate when Hill County was formed. A 260 acre donation was accepted from John A. Caruthers, Thomas M. Steiner, and Jonathan Newby to create the county seat named Hillsborough. Cincinnatus Ney Brooks was elected to serve as County Clerk and District Clerk in the new county, and he constructed the first log courthouse in 1853 on the courthouse square. When the Hillsborough post office was established in August 1854, Brooks was named the first postmaster. The spelling was changed to Hillsboro in July 1888. In 1854 the elm-log courthouse was replaced by a frame building, and in 1872 a two-story brick building was erected. That building burned on September 18, 1872 and was replaced by a two-story brick courthouse that served until 1889. The present courthouse was erected in 1889-1890, designed by W. C. Dodson and built with Bell County limestone by contractor Tom Lovell for $83,000. The historic courthouse suffered a major fire on January 1, 1993, but after restoration was rededicated in 1999. Restoration was spearheaded by Dallas architect Craig Melde, principal with ArchiTexas and by R. J. King Construction Company.
The following link shows the properties that are included in the Downtown and Residential Historic Districts: