The town of Maiori boasts the longest beach on the coast. It was the seat of the Customs of the Admiralty. Today, the main street is a pedestrian area and popular shopping destination. The magnificent fortified citadel of San Nicola De Thoro Plano rises up behind the town. The citadel is capable of housing one thousand people. It is currently privately owned, but it is open to visitors. Visit the Santa Maria De Olearia Abbey, also known as the catacombs, made up of three places of worship with a wealth of frescoes, painted by un-named abbots. The name Olearia derives from the nearby olive mill. By boat, visit the Annunziata Grotto (with its small lake), the Acqua Sulfurea Grotto (curative spa waters for skin conditions), the Pannona Grotto with its multi-coloured stalactites and stalagmites, and the Porta di Monte Piano grotto, of particular speleology interest.