One of the great rulers of the Anuradhapura period was Dutugemunu (fl.100 BC ), who is famous for having saved Ceylon and its religion from conquest by Indian invaders. Mahasen, a king in the 3d century AD , built many fine dagobas and other monuments that delight and amaze visiting art lovers. The classic period of Ceylonese art flourished under Kassapa, a king of the 5th century. The great figure of the Polonnaruwa period was Parakramabahu I (the Great, r.1153–86), who unified the government of Ceylon, built many magnificent structures, and organized the economy. The most famous political figure in modern Ceylon was Don Stephen Senanayake (1884–1952), leader of the independence movement and first prime minister of independent Ceylon. Solomon West Ridgway Dias Bandaranaike (1899–1959), prime minister from 1956 to 1959, is regarded as the founder of Ceylon as a socialist state. His widow, Sirimavo Bandaranaike (b.1916), was prime minister during 1960–65, 1970–77, and was appointed again in 1994. Her daughter, Chandrika Bandaranaike Kumaratunga (b.1946) was elected president in 1994. Junius Richard Jayewardene (1906–96), who helped usher in economic reforms and a free enterprise system, became Sri Lanka's first president in 1978 and served until 1982. Science-fiction writer Sir Arthur C. Clarke (b. England, 1917) is one of Sri Lanka's most famous expatriate residents. Born in Sri Lanka, Canadian author and poet Michael Ondaatje (b.1943) received the 1992 Booker McConnell Prize for his novel The English Patient .