On May 15 of 1865, it was decided that a new courthouse was needed. Micajah Stanley, an early settler, donated 8 lots of land for the building of a new courthouse. On January 2, 1866 building began. The building was to include 2 vaults and a basement housing the jail and living quarters for the janitor. As winter came on the building was completed on November 1st, 1866. The total cost of the building was $28,000. In 1893, a new jail was built on the corner of Third and Cherry Streets. After the completion of that jail the one in the basement was no longer used. In 1962, land was left by Kathryn Clifton for the building of a new courthouse and jail. In 1964 the new jail opened and in 1965 the new courthouse opened. After the new courthouse was opened the Old Courthouse fell into disrepair for 3 years until the Iroquois County Historical Society formed and restored the courthouse as a museum. On June 13, 1975 the Old Courthouse was registered as a Historic Place by the United States Department of the Interior.