Nant Gwrtheyrn is a Welsh Language and Heritage Centre, located near the village of Llithfaen on the northern coast of the Llŷn Peninsula, Gwynedd, in northwest Wales.
It is sometimes referred to as 'the Nant' and is named after the valley where it was located, Nant Gwrtheyrn ("Vortigern's Creek"), which lies in isolation by the sea at the foot of Yr Eifl. The centre is built within the structures of the former quarrying village Porth y Nant, which was abandoned mid-way through World War II after the cessation of quarrying.
The quarry named Nant Gwrtheyrn opened in 1861, and was serviced by a village on the site of the current language centre called Porth y Nant. Nant Gwrtheyrn produced setts used for road surfacing. The community lived an isolated existence, with product shipped and goods shipped out mainly via the Irish Sea, resulting limited contact with the outside world.
The quarry closed early in World War II, partly due to a drop in demand and also to transport difficulties. The hillsides of the Nant, through their landscape scars and the ruins of quarry structures, testify to this former existence.
After the quarry was closed, the community dispersed and the cottages fell into disrepair. Occupied by hippies for a time during the 1960s, the site was the subject of several plans for redevelopment, including as an approved school, when it was acquired by a local trust set up to establish a Welsh language centre there.
The centre specialises in courses for adults who want to learn Welsh as a second language. Courses are held throughout the year at a variety of levels from absolute beginner up to Higher and Proficiency levels, with learners' weekends and other activities to strengthen understanding. Course participants usually are offered one or two cultural experiences as well as formal teaching. Accommodation for students is available in the village, which consists of two terraces of former workmen's cottages, Trem y Mor (Sea View) and Trem y Mynydd (Mountain View).
The centre is used in addition for weddings and conferences, and as a residential site for Writing students at Liverpool John Moores University. The countryside surrounding Nant Gwrtheyrn is known for its outstanding natural beauty, and frequented for this by writers and photographers.