The oldest building in Staines, Surrey is believed to be St. Mary's Church. The church dates back to the 12th century, although parts of the structure may be even older. St. Mary's Church is located on Church Street, near the town center. It is a Grade I listed building and has a rich architectural and historical heritage. The church features Norman and Gothic elements and has undergone various alterations and additions over the centuries. St. Mary's Church serves as a significant landmark in Staines and stands as a testament to the town's long history.