Twmbarlwm also known as Twm Barlwm, Twyn Barlwm, or locally known as "The tump" in relation to the mound that lies on its summit, is a mountain situated 2km to the northeast of Risca in South Wales. It is (1,375ft/419m) high and is a well known sight throughout the region. It commands extensive views across what is now the M4 corridor, out over the Bristol Channel and Newport and Cwmbran.
The top of the mountain features the remains of what is presumed to be an Iron Age hill fort near its summit, believed to have been built by the Silures, the Celtic tribe that inhabited the area before and during Roman times. This is the reason for the local people of Risca and Cwmcarn naming it "The tump". There was also thereafter possibly a Roman signal point and there is also a substantial Norman motte and bailey castle incorporated into the eastern end of the fort, probably of early Norman construction.