To the north it overlooks the sea of Conwy Bay, and to the south lie the foothills of the Carneddau range of mountains, of which it forms a part.

Mynydd y Dref is the remains of an ancient volcano that erupted about 450 million years ago.

Castell Caer Seion comprised a stone walled fort, and remains show this to have been an extensive site, incorporated more than 50 hut circles and levelled platform houses, and with a citadel and outposts.

No datable remains were found, only slingstones, querns and stone pestles and mortars, which suggests that, unlike many hillforts in north Wales, this site was not reoccupied in the late Roman period.

[4] Tracks and footpaths cross Mynydd y Dref, and many walks, which can be accessed from Sychnant Pass at its western end.