The 1883 eruption of Krakatoa caused a tsunami that damaged Menara Martello, which the Dutch East India Company built in 1850 on Bidadari Island (Pulau Bidadari), one of the Thousand Islands (Kepulauan Seribu), as part of a set of fortifications that protected the approaches to Batavia. Photos suggest that Martello Menara was not a true Martello, but rather a circular fort. The tower was operational until 1878, when it became a storage site, and was abandoned in 1908. Bidadari Island was also known as Pulau Sakit (Sick Island) as it housed a leper colony during the 17th century. More recently, the island came to be called "Angel Island", to honour the leprosarium that had been there.