Moel y Gaer, Llantysilio

Moel y Gaer (Welsh for "bald hill of the fortress") is an Iron Age hillfort on a summit of Llantysilio Mountain, northwest of the town of Llangollen, Denbighshire, Wales. The site is a scheduled monument classified as a prehistoric defensive hillfort.

The hillfort is also protected and managed as part of the Heather and Hillforts Project. The project includes six hillforts: the four most southerly of the hillforts in the Clwydian Range (Penycloddiau, Moel Arthur, Moel y Gaer Llanbedr, and Moel Fenlli), this hillfort and Caer Drewyn.

Description
The defensive works at Moel y Gaer comprise a roughly oval area measuring about 140 m east-west by 100 m, enclosing approximately 0.95 ha, and consist of a single rampart and a discontinuous ditch, with a single entrance on the eastern side. The stone bank is up to 3.1 m high externally and 0.6 m internally, and the ditch to the north is 10 m wide. The summit reaches 503.5 m above sea level. A track crossing the site from east to west, used by pedestrians and drivers of off-road vehicles, presents a threat to the archaeological remains.

Excavations and surveys
As part of the Heather and Hillforts Project a topographic survey was commissioned, which took place between December 2006 and January 2007. The survey recorded the remains of 11 roundhouse platforms within the enclosure, concentrated on the eastern side. A geophysical survey followed in 2009, which identified more possible roundhouses, along with possible internal tracks and two potential rectangular structures.

In 2010 an archaeological excavation identified two roundhouses of about 7 m diameter from different periods of occupation, and the results showed preservation of significant archaeological deposits in the interior of the hillfort, but also the fragile nature of the resource.