Situated on top of the mountain between the Taff and Aber Valleys, this walk has a strangely timeless feel, which is even stranger, considering it was located in the eye of the storm created by the Industrial Revolution.

Eglwysilan means Ilan's church, but very little is known about him, although there is a tradition that says he was one of the pre-Norman bishops of Llandaff and a disciple of St. Illtud. There is a village named St. Ilan in Northern Brittany close to St Brieuc, who is also thought to have come from this area. St. Briavels, now over the border in England, is named after him. In the calendar of Welsh saints, March 9th has been dedicated to his memory.

The Book of Llandaff, which was compiled around 1100, calls the church Merthyr Ilan - the place where his relics were kept (compare Merthyr Tydfil - where Tydfil's relics were kept). When the parish was created in the 12th century, it covered an area of more than 30,000 acres, which stretched all the way from Rumney to Abercynon, which is a huge area, but at the time, it had a small population.