The Downtown Mount Vernon Historic District was listed on the National Register of Historic Places on February 3, 2012. The Downtown District is primarily concentrated around the Public Square and along South Main Street. Many of the buildings have Italianate influences, although Federal, Greek Revival, Richardsonian-Romanesque, Queen Anne, Art Deco/Moderne, and Colonial Revival are also represented.
This district encompasses the original commercial district of the City of Mount Vernon, and serves as the anchor for three additional residential districts previously listed on the National Register: North Main - North Gay Streets Historic District, East High Street Historic District, and East Gambier Street Historic District.
The majority of the buildings retain much of their original architectural features, the earliest building dating back to 1829. The streets are lined with small ornamental trees, flowerbeds, and decorative street lamps that were designed and selected to replicate gas lamps that once lined the streets, completing the vision of an early Ohio town of the 19th century.