The canal's most notable features include the spectacular Pontcysyllte Aqueduct, an aqueduct engineered by Telford to carry the canal over the valley of the River Dee east of Llangollen (the Dee also supplies the canal with water, taken from the weir at the Horseshoe Falls, about three miles west of Llangollen). Another aqueduct carries the canal over the River Ceiriog at Chirk; there are tunnels nearby at Whitehouses and Chirk, and another south-east of Ellesmere.