In typically ostentatious style, the Romans built a bathhouse complex above Bath's 46°C (115°F) hot springs. Set alongside a temple dedicated to the healing goddess Sulis-Minerva, the baths now form one of the world's best-preserved ancient Roman spas, and are encircled by 18th- and 19th-century buildings. To dodge the worst of the crowds avoid weekends, and July and August; buy fast-track tickets online to by-pass the queues. Saver tickets covering the Roman Baths and the Fashion Museum cost adult/child/family £22.50/12.25/58.
The heart of the complex is the Great Bath, a lead-lined pool filled with steaming, geothermally heated water from the so-called 'Sacred Spring' to a depth of 1.6m. Though now open-air, the bath would originally have been covered by a 45m-high barrel-vaulted roof.
More bathing pools and changing rooms are to the east and west, with excavated sections revealing the hypocaust system that heated the bathing rooms. After luxuriating in the baths, Romans would have reinvigorated themselves with a dip in the circular cold-water pool.
The King's Bath was added sometime during the 12th century around the site of the original Sacred Spring. Every day, 1.5 million litres of hot water still pour into the pool. Beneath the Pump Room are the remains of the Temple of Sulis-Minerva.
Digital reconstructions pop up in some sections of the complex, especially in the Temple Courtyard, and the West and East Baths, which feature projections of bathers. There is also a fascinating museum displaying artefacts discovered on the site. Look out for the famous gilded bronze head of Minerva and a striking carved gorgon's head, as well as some of the 12,000-odd Roman coins thrown into the spring as votive offerings to the goddess.
The complex of buildings around the baths was built in stages during the 18th and 19th centuries. John Wood the Elder and the Younger designed the buildings around the Sacred Spring, while the famous Pump Room was built by their contemporaries, Thomas Baldwin and John Palmer, in neoclassical style, complete with soaring Ionic and Corinthian columns. The building now houses a restaurant, where offerings include magnificent afternoon teas (£26, or £35 with champagne). You can also taste free samples of the spring waters, which were believed in Victorian times to have curative properties. If you're lucky, you might even have music provided by the Pump Room's string trio.
Admission to the Roman Baths includes an audio guide, featuring commentary in 12 languages – there's also one especially for children and a guide in sign language. One of the English guides is read by bestselling author Bill Bryson. Free hourly guided tours start at the Great Bath on the hour. The last entry to the complex is an hour before closing.