St. Helier is the capital and the largest town on the island of Jersey. Proud Elizabeth Castle is built on an island in the bay and can only be reached at low tide. Fort Regent is built on a rockface overlooking the town and has been converted into a recreation centre with sports and conference facilities, an aquarium, postal museum, fair, swimming pool and a series of sports halls. The Jersey Museum in Pier Street is also worth a visit. The best shopping district in the city is the area around King Street and Queen Street. Most luxury goods are less expensive here than on the UK mainland, but they are not duty free.