Begun in 1847, Lafayette County's third courthouse is the oldest remaining courthouse in use in Missouri. The early portion, with its columned portico, remains unchanged except for modern lighting, heating, and office equipment. The office wing on the east side was begun in 1854 as a one-story building, and a second story was added afterward. In 1939 it was connected to the main courthouse, providing new vaults and offices. During the Battle of Lexington, September 18-20, 1861, a cannon ball struck the east column and remains in place. The cupola was part of the original construction, but the clock was installed in 1886 by Lexington citizens.