The first headmaster of the Calvert School, Virgil Hillyer, built Castalia between 1928 and 1929, naming it after the spring at the foot of Mount Parnassas in Italy that is said to have been the inspiration for the muses. The prominent Baltimore architect Francis Hall Fowler was the architect of this Italian villa-inspired house. In 2006, the Calvert School acquired the building and proposed to demolish it for an outdoor amphitheater.
The Tuscany Canterbury Neighborhood Association led the effort to save the building, with Baltimore Heritage filing a successful nomination for the building to be added to the city’s historic landmark list in 2008. The building is now on the landmark list and the Calvert School has begun plans to preserve it for a school-related use.