The summit, 1,158 feet (353 metres) above sea level, is encircled by the wall of a late-prehistoric hillfort, a tribal centre of the Votadini called in Brythonic and Old Welsh Din Gefron, from which the name stems (Old English *geafringa-).

The hillfort encloses an area of approximately 12 acres (4.9 ha) and is enclosed by a stone wall, upwards of 10 ft (3.0 m) thick, having four entrances, one of which is defended by a guard-house; and within this area is an inner fort, excavated out of the rock, of an oval form, measuring 13 ft (4.0 m) across at the widest part.

On the sides of the hill, and in a high valley between the Bell and the next hill, called Whitelaw, there are many remains of stone huts rudely flagged, some in groups surrounded by rampiers (ramparts), and others isolated.

The buildings of the hillfort would have been bright pink when first constructed, being made from local andesite.

This stone is pink when quarried and turns, after a few years’ exposure to the elements, to a dull grey.