There are two separate Iron Age earthworks on this hill. Coflein descriptions:
Tump Wood Camp (SO11272150)
Tump Wood Camp is a multivallate hilltop enclosure, with an internal area of c.120m by 68m.
Pen-y-Wenallt enclosure (SO11162095)
The partly bulldozed, sub-rectangular enclosure at Pen-y-Wenallt measures 55m N-S by 42m, and is defined by scarps, or banks, and ditches.