Moel y Gaer (Welsh for "bald hill of the fortress") is an Iron Age hillfort located on a summit at the southern end of Halkyn Mountain, overlooking the village of Rhosesmor, Flintshire, Wales. It is a well-preserved hillfort overlooking the Dee Estuary. Excavations in the early 1970s revealed a sequence of defensive structures made of timber and several phases of building work inside the ramparts.