Tucked inside the Governor Calvert House in Annapolis, Maryland, is a hypocaust—an early heating system discovered during excavations. Inspired by ancient Roman technology, this system worked by circulating hot air under the floors. Built in the 17th or early 18th century, it was not only used to heat the house but also to grow plants and citrus in colder months.
The Governor Calvert House is a historic building in downtown Annapolis. Built in the late 1600s, it was once home to Charles Calvert, the fifth Lord Baltimore, who played an important role in Maryland’s early history.
Over the years, it has been renovated and expanded, combining its original colonial style with modern features. A 20th-century archaeological dig discovered the hypocaust, which can be seen under a plexiglass floor.