Caerphilly is a town in Glamorgan, standing at the southern end of the Rhymney Valley, on the border with Monmouthshire, with a population of some 31,000 souls. It is a commuter town for Cardiff and Newport, which are located some 7½ miles and 12 miles away respectively. Caerphilly is separated from the Cardiff suburbs of Lisvane and Rhiwbina by Caerphilly Mountain.
The town gives its name to Caerphilly cheese, which originated in the area.
Caerphilly hosted the National Eisteddfod in 1950.