Many ancient standing stone monuments were erected during the prehistoric period; amongst the best known are Stonehenge, Devil's Arrows, Rudston Monolith and Castlerigg. With the introduction of Ancient Roman architecture there was a development of basilicas, baths, amphitheaters, triumphal arches, villas, Roman temples, Roman roads, Roman forts, stockades and aqueducts. It was the Romans who founded the first cities and towns such as London, Bath, York, Chester and St Albans. Perhaps the best-known example is Hadrian's Wall stretching right across northern England. Another well-preserved example is the Roman Baths at Bath, Somerset.