Moel y Gaer Llantysilio (SJ167464) sits on a low summit between Moel Gamelin and Moel Morfydd on the Llantysilio Mountains.

It is the smallest and simplest of all the hillforts within the Heather and Hillforts project area.

It is a univallate hillfort, with the single rampart enclosing an area of just one hectare.

There is a single, inturned entranceway and traces of hut platforms.

It appears that there has been no excavation of the site.

In 2007 EAS carried out a topographical survey of the site.

As part of the survey they noted that the location of the hillfort has views over the River Dee and the River Alyn.

Eleven potential hut platforms were noted within the interior of the hillfort.