St. Peters is a city in St. Charles County, Missouri, United States. Interstate 70 passes through the city, providing a major transportation link.St. Peters was named the 60th best place to live by Money magazine, putting it at the top in the state of Missouri. It also ranked number 60. The "Rec-Plex" in St. Peters is an award-winning recreation and fitness complex that underwent an $18.5 million expansion in 2007. The city also hosts the county's largest shopping center, Mid Rivers Mall, which plans a 120,000 sq ft (11,000 square kilometers) expansion.