CAERPHILLY, a market town of Glamorganshire, Wales, 1524 m.
Long, under Cefn Onn, a direct line was provided from Caerphilly to Cardiff.
The Pontypridd and Newport railway was constructed in 1887, and there is a joint station at Caerphilly for both railways.
The ancient commote of Senghenydd (corresponding to the modern hundred of Caerphilly) comprised the mountainous district extending from the ridge of Cefn Onn on the south to Breconshire on the north, being bounded by the rivers Taff and Rumney on the west and east.
To keep these in check, Gilbert de Clare, during the closing years of the reign of Henry III., built the castle of Caerphilly on the southern edge of this district, in a wide plain between the two rivers.