Thermae Bath Spa £45 million. Thermae Bath Spa eventually opened to the public on 7 August 2006, ending a 28-year period during which the waters remained unavailable for bathing. The spa is largely sited in a new 'Glass Cube' building by Sir Nicholas Grimshaw, near the site of the ancient Royal Bath, which has been interlinked with historic Georgian spa buildings such as the nearby Hot and Cross Baths. The building is in a strongly contemporary style in contrast to its Georgian surroundings. The complex houses both traditional and modern spa facilities. A 2014 survey indicated the spa attracted an extra 260,000 visitors
Ancient Roman architecture of these developments are described by Vitruvius, writing in the first century AD in his work De Architectura. Although concrete had been used on a minor scale in Mesopotamia, Roman architects perfected Roman concrete and used it in buildings where it could stand on its own and support a great deal of weight. The first use of concrete by the Romans was in the town of Cosa sometime after 273 BC. Ancient Roman concrete was a mixture of lime mortar, aggregate, pozzolana, water, and stones, and was stronger than previously-used concretes. The ancient builders placed these ingredients in wooden frames