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.
This building was designed in 1898 by prominent architect Jerome B. Legg, who also designed County Courthouses in the Missouri counties of Ste. Genevieve, Gasconade, Mississippi and St. Francois. They were all brick buildings. The stone for this building was quarried on site, and is the only one Legg built with stone. It is considered his best effort.
This Courthouse building was started in February 1900 and occupied in April 1903. A dedication was to have been held in June 1903, but a major flood of the Missouri River that year canceled the dedication.
The Courthouse was finished in 1905, but the official dedication wasn't held until Oct. 31, 1913. The total cost of this structure, including land, was $94,582.87.
After the construction of the new Administration Building and the Courts Administration Building, major renovations of the Historic Courthouse took place in 1994. Some of the challenges in this renovation were lead and asbestos cleanup, making it accessible for persons with disabilities, returning original finishes and colors of the day, and stabilizing painted murals.
Some notable features that were conserved from the original courthouse include mosaic floor tiles, wainscoting, granite steps, original wrought iron railings and the exterior dome.