Caerphilly (Welsh Caerffili) is a city in Wales, United Kingdom with 31,060 inhabitants (2001). Caerphilly is the namesake and largest city in the county of Caerphilly. It lies in the Rhymney Valley in South Wales Coalfield about eleven kilometers north of Cardiff. it is famous for its medieval fortress - a moated castle named Caerphilly Castle. The city is also of origin and namesake of the cheese Caerphilly, who is also the occasion for the annual summer Big Cheese Festival, which numbered up to 80,000 visitors in recent years.