Frontenac is a wealthy inner-ring suburb of St. Louis, located in St. Louis County, Missouri, United States. The signature landmark is Plaza Frontenac, a high-end mall featuring many prominent retailers such as Saks Fifth Avenue, Neiman Marcus, and Tiffany & Co., among others. The population was 3,482 at the 2010 census. The community name is inspired by the Château Frontenac of Quebec City.