Dinas Emrys (Welsh: fortress of Ambrosius) is a rocky and wooded hillock near Beddgelert in Gwynedd, north-west Wales. Rising some 250 ft above the floor of the Glaslyn river valley, it overlooks the southern end of Llyn Dinas in Snowdonia. Little remains of the castle structures that once stood here, save its stone ramparts and the base of a keep. Some believe the castle was erected by Llewelyn the Last to guard the road to the mountain pass of Snowdon.