In Wales Illustrated in a Series of Views by Henry Gastineau, published in 1810, it states: "Near the town are some remains of an ancient fortress called Castell Cadwgan, thought to have been erected by king Cadwgan, about the year 1148."
Terwyn was brought up in the Aeron Valley, Ceredigion, and was educated at Felinfach Primary School and then at Aberaeron Comprehensive School.
It is crossed, almost at the summit by an ancient drovers road now classified as the B4337 road which gave access from the northern parts of Ceredigion to South Wales before the coastal route down to Aberaeron was developed.
The Castle Hotel, Aberaeron is located in a Grade II listed building in the coastal town of Aberaeron, Ceredigion, West Wales.