The island and its natural harbour were used by Arab merchants as a maritime trading centre from the 10th to the late 15th century. The Portuguese explorer Vasco da Gama (Gama, Vasco da), who landed on the island in 1498, claimed it for Portugal. Four years later he returned with Portuguese settlers, who built the first fortress, St. Gabriel (1507–08; no longer standing). The town assumed prominence in Portugal's campaign to take over trade with India and the East Indies. The later fort of St. Sebastian was begun in the mid-16th century and is distinguished by its Italian Renaissance architecture; it withstood attack by the Dutch in 1607, and its massive walls still stand. The relative importance of the island decreased after the decline in the slave trade in the mid-19th century and the opening of the Suez Canal (1869). By 1907 the colonial government was transferred to Lourenço Marques (now Maputo), and in the mid-20th century, Moçambique's maritime trade was largely diverted to the new port of Nacala, on the mainland coast farther north. A bridge has linked the island to the mainland since 1967.