Britain's most inland commercial dock, connected to the Severn by a ship canal opened in 1827. The Victorian warehouses around the basin have been carefully restored and now house several museums, cafes, and shops. The National Waterways Museum here is particularly good — it covers the whole history of Britain's canal network, with a fleet of historic boats moored outside.
The Regiments of Gloucestershire Museum and the Robert Opie Collection (a vast archive of packaging and advertising) are also based here. The docks themselves are still working to a degree, and the mix of old warehousing, water, and boat traffic makes for an atmospheric wander even if you skip the museums.