Cefn Eglwysilan

Cefn Eglwysilan is a hilltop with two peaks in Wales, its main summit topped by a wireless transmission station and its southern peak marked by a triangulation point. The hill rises to about 380 meters and is crossed by several public byways that offer different ways for visitors to reach and explore it.

The hill carries the Senghenydd Dyke on its eastern slope, an ancient earthwork that marked the boundary of a 13th-century deer park linked to nearby Caerphilly Castle. This earthwork shows how the area once served as hunting grounds for the castle.

The name comes from the nearby hamlet of Eglwysilan, home to a church dedicated to Saint Ilan that reflects local Welsh religious roots. This connection shows how the hill remains tied to the community's spiritual history.

Multiple public byways cross the hill, connecting Eglwysilan Road with routes between Nelson and Senghenydd, offering various entry points. It is best to wear suitable footwear and be prepared for changing weather, as the summit is quite exposed.

The geological makeup consists of Hughes Sandstone from the Carboniferous Period, with underlying siltstone and mudstone layers reaching back about 309 million years. This ancient rock formation makes the hill a window into a very distant geological past.

Location: Wales

Location: Rhondda Cynon Taf

Elevation above the sea: 382 m

GPS coordinates: 51.60612,-3.30521

Latest update: December 14, 2025 18:40