Most of Bath’s buildings are made from the local, golden-coloured, Bath Stone. The dominant architectural style is Georgian,[8] which evolved from the Palladian revival style that became popular in the early 18th century. The city became a fashionable and popular spa and social centre during the 18th century. Based initially around its hot springs, this led to a demand for substantial homes and guest houses. The key architects, John Wood and his son, laid out many of the city’s present-day squares and crescents within a green valley and the surrounding hills. According to UNESCO this provided… “an integration of architecture, urban design, and landscape setting, and the deliberate creation of a beautiful city”.