NEWPORT , the capital of the Isle of Wight, sits at the centre of the island at a point where the River Medina's commercial navigability ends. Apart from a few pleasant old quays dating from its days as an inland port, the town isn't particularly engaging, content to fulfil its role as the island's municipal and commercial centre. Newport's main attraction is Carisbrooke Castle (daily: April-Sept 10am-6pm; Oct 10am-5pm; Nov-March 10am-4pm; £4.50; EH), a hilltop fortress on the southwest outskirts. The austere Norman keep's most famous visitor was Charles I, detained here (and caught one night ignominiously jammed between his room's bars while attempting escape) prior to his execution in London. The museum in the centre of the castle features many relics from his incarceration, as well as those of the last royal resident, Princess Beatrice, Queen Victoria's youngest daughter. The castle's other notable curiosity is the sixteenth-century well-house, where donkeys still trudge inside a huge treadmill to raise a barrel 160ft up the well shaft.