Smithonia is a historic site in the U.S. State of Georgia. The land was part of Georgia agricultural tycoon and state legislator James Monroe Smith (Georgia planter)'s property holdings. It was built in 1866 in a "Plantation Plain" architectural style. The nearest city is Comer, Georgia but Smithonia, Georgia is now a distinct location. The Smith and Dunlap Railroad connected the property with the Georgia Railroad at Dunlap, Georgia. The rail line was also used to construct Howard's Covered Bridge. The building was listed on the National Register of Historic Places in 1984.