The Historic County Courthouse, located at 100 N. Third Street, houses the offices of the County Executive, County Counselor, County Council and the Director of Administration.
St. Charles County, organized in 1812, purchased the site for a permanent location from the City of St. Charles in 1851 for $223.87. Two modest buildings were constructed, one for the County Clerk and the other for the Circuit Clerk.
For years, this location was known as "Clerks' Hill."
The people of St. Charles County twice defeated proposed bond issues to build a new courthouse. In 1888 and 1894, the bond issues proposals lost by heavy margins. They needed two-thirds approval margins to pass. In 1897, at the request of the St. Charles Merchants Association, the Republican County Court ignored the popular votes and proceeded with the project, paying for it from surplus county funds.
The county seat, with a population of 7,982 after the 1900 census, had become an industrial center, with the car shops of American Car and Foundry visible from the new courthouse.