The County Museum contains many Roman artefacts. The Romans built an aqueduct to supply the town with water. It was rediscovered in 1900 as the remains of a channel cut into the chalk and contouring round the hills. The source is believed to be the River Frome at Notton, about upstream from Dorchester. Near the town centre is Maumbury Rings, an ancient British henge earthwork converted by the Romans for use as an amphitheatre, and to the north west is Poundbury Hill, another pre-Roman fortification.