The Second Severn Crossing (Welsh: Ail Groesfan Hafren) is the M4 motorway bridge over the River Severn between England and Wales, inaugurated on 5 June 1996 by HRH The Prince of Wales to augment the traffic capacity of the original Severn Bridge built in 1966. The bridge marks the lower limit of the River Severn and the start of the Severn Estuary.