In the medieval period the River Parrett was used to transport Hamstone from the quarry at Ham Hill, Bridgwater was part of the Port of Bristol until the Port of Bridgwater was created in 1348, covering of the Somerset coast line, from the Devon border to the mouth of the River Axe. Historically, the main port on the river was at Bridgwater; the river being bridged at this point, with the first bridge being constructed in 1200 AD. Quays were built in 1424; with another quay, the "Langport slip", being built in 1488 upstream of the Town Bridge. A Customs House was sited at Bridgwater, on West Quay; and a dry dock, launching slips and a boat yard on East Quay. The river was navigable, with care, to Bridgwater Town Bridge by vessels. By trans-shipping into barges at the Town Bridge the Parrett was navigable as far as Langport and (via the River Yeo) to Ilchester.