From the World Heritage inscription:
The Roman remains, especially the Temple of Sulis Minerva and the baths complex (based around the hot springs at the heart of the Roman city of Aquae Sulis, which have remained at the heart of the City’s development ever since) are amongst the most famous and important Roman remains north of the Alps, and marked the beginning of Bath’s history as a spa town.
The Georgian city reflects the ambitions of John Wood Senior, Ralph Allen and Richard ‘Beau’ Nash to make Bath into one of the most beautiful cities in Europe, with architecture and landscape combined harmoniously for the enjoyment of the spa town’s cure takers.
The Neo-classical style of the public buildings (such as the Assembly Rooms and the Pump Room) harmonises with the grandiose proportions of the monumental ensembles (such as Queen Square, Circus, and Royal Crescent) and collectively reflects the ambitions, particularly social, of the spa city in the 18th century.
The individual Georgian buildings reflect the profound influence of Palladio, and their collective scale, style, and the organisation of the spaces between buildings epitomises the success of architects such as the John Woods, Robert Adam, Thomas Baldwin, and John Palmer in transposing Palladio’s ideas to the scale of a complete city, situated in a hollow in the hills and built to a Picturesque landscape aestheticism creating a strong garden city feel, more akin to the 19th century garden cities than the 17th century Renaissance cities.
Bath might just be the most charming city in England. While originally built and best known for its Roman baths, it is also an excellent showcase of English Georgian architecture. The city has a whole is very walkable and I found it to be one of the highlights of England.
In addition to the Roman baths, Bath is home to Bath Abbey, the Fashion Museum and a host of Georgian buildings. The riverfront area is especially picturesque.
View my complete list of UNESCO World Heritage sites.