Roman Baths Bath
The Roman Baths themselves are below the modern street level. There are four main features: the Sacred Spring, the Roman Temple, the Roman Bath House and the Museum holding finds from Roman Bath. The buildings above street level date from the 19th century.
The first shrine at the site of the hot springs was built by Celts, and was dedicated to the goddess Sulis, whom the Romans identified with Minerva.
The name Sulis continued to be used after the Roman invasion, leading to the town's Roman name of Aquae Sulis (literally, "the waters of Sulis"). The temple was constructed in 60-70 AD and the bathing complex was gradually built up over the next 300 years. During the Roman occupation of Britain, and possibly on the instructions of Emperor Claudius,] engineers drove oak piles to provide a stable foundation into the mud and surrounded the spring with an irregular stone chamber lined with lead. In the second century it was enclosed within a wooden barrel-vaulted building, and included the caldarium (hot bath), tepidarium (warm bath), and frigidarium (cold bath). After the Roman withdrawal from Britain in the first decade of the fifth century, these fell into disrepair and were eventually lost due to silting up, and flooding.
The baths have been modified on several occasions, including the 12th century when John of Tours built a curative bath over the King's Spring reservoir and the 16th century when the city corporation built a new bath (Queen's Bath) to the south of the Spring. The spring is now housed in eighteenth century buildings, designed by architects John Wood, the Elder and John Wood, the Younger, father and son. Visitors drank the waters in the Grand Pump Room, a neo-classical salon which remains in use, both for taking the waters and for social functions.
Credit to Wikipedia for this information.