Public bathing 19 BC had a rotunda 25 metres across, circled by small rooms, set in a park with artificial river and pool. By AD 300 the Baths of Diocletian would cover , its soaring granite and porphyry sheltering 3,000 bathers a day. Roman baths became "something like a cross between an aquacentre and a theme park", with pools, game rooms, gardens, even libraries and theatres. One of the most famous public bath sites is Aquae Sulis in Bath, England. Dr. Garrett G Fagan, a professor at Pennsylvania State University, described public bathing as a "social event" for the Romans in his
Geothermal energy a renewable energy source like geothermal. But as a result of government assisted research and industry experience, the cost of generating geothermal power has decreased by 25% over the past two decades. In 2001, geothermal energy costs between two and ten US cents per kWh. Hot springs have been used for bathing at least since Paleolithic times. The oldest known spa is a stone pool on China's Lisan mountain built in the Qin Dynasty in the 3rd century BC, at the same site where the Huaqing Chi palace was later built. In the first century AD, Romans conquered "Aquae Sulis",