The Sandusky County Courthouse is a local government building in Fremont, Ohio, United States. Built in the 1840s and since greatly modified, it remains in use by the government of Sandusky County. Construction on the Sandusky County Courthouse began in 1840 and concluded four years later. Built according to a design by architect Cyrus Williams, it includes a dungeon-style underground jail with ashlar walls built of large blocks of locally quarried limestone. Built primarily of stone and brick, the courthouse possesses a Greek Revival facade composed of Doric columns. Its original appearance has been drastically altered; when built, the portico comprised six wooden columns, rather than the eighteen sandstone ones now present, and an octagonal cupola with a round copper dome was present ato