Sudbrook, Monmouthshire the Silures from the 2nd century BC and occupied by the Romans from the 1st century AD until the 4th century. The hillfort was originally much bigger than now having been eroded over the centuries. Finds of Roman coins at Black Rock, Portskewett, show that the ferry crossing was in use in Roman times, on the route between the Roman stations of "Aquae Sulis" (Bath) and "Venta Silurum" (Caerwent). According to tradition, Caradog Freichfras, the Welsh ruler of Gwent in the 5th century or 6th century AD, moved his court from Caerwent to the Portskewett area, possibly to the fort.
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",