St. Marys College was a Roman Catholic school in Ilchester, Maryland (Illchester Mills) near modern Ellicott City, Maryland in Howard County. The ruins are near Ilchester and Bonnie Branch roads. The upper college building was built in 1868 consisting of a cupola topped eighteen bay by five bay building with a five by five bay projection. A three by three bay, five story "L" shaped addition is included, with all of the structure on a stone foundation. A three-story chapel was attached to the building in 1882. In 1934 a fifth floor was added throughout. A statue of Madonna with Child was situated in a niche.