this was originally the site of a causeway across the river dee. the weir was built in sandstone in 1093 for hugh lupus, 1st earl of chester, for the benedictine abbey of st werburgh (now chester cathedral). it was designed to provide a head of water for the medieval mills on the river. the mills were demolished during the 20th century and the weir was restored to serve the chester city council's hydro-electric power station, which operated from 1913 to 1939 on the site of the former mills.