Valle Crucis Abbey (Valley of the Cross) is a Cistercian abbey located in Llantysilio in Denbighshire, Wales. More formally the Abbey Church of the Blessed Virgin Mary, Valle Crucis it is known in Welsh both as Abaty Glyn Egwestl and Abaty Glyn y Groes. The abbey was built in 1201 by Madog ap Gruffydd Maelor, Prince of Powys Fadog. Valle Crucis was dissolved in 1537 during the Dissolution of the Monasteries, and subsequently fell into serious disrepair. The building is now a ruin, though large parts of the original structure still survive.