Note: Located on the west bank of the River Ouse; it was a market center and important river port until Newhaven on the coast took prominence. The town grew around the 11th-century castle and priory, the ruins of which still dominate the town. Simon de Montfort defeated Henry III at the Battle of Lewes on May 14, 1264. Lewes is the site of 16th-century Barbican House, the home of Anne of Cleves, fourth wife of Henry VIII. Lewes is now the county seat of East Sussex. The nearby town of Glyndebourne is a world-famous opera center.