<Table> <Tr> <Th_colspan="2"> Robben Island Robbeneiland </Th> </Tr> <Tr> <Td_colspan="2"> Robben Island Village </Td> </Tr> <Tr> <Td_colspan="2"> Robben Island Robben Island Robben Island Show map of Western Cape Show map of South Africa Show map of Africa Show all Robben Island shown within Western Cape </Td> </Tr> <Tr> <Td_colspan="2"> Location within Cape Town (show) Robben Island </Td> </Tr> <Tr> <Td_colspan="2"> Coordinates: 33 ° 48 ′ 24" S 18 ° 21 ′ 58" E ﻿ / ﻿ 33.806734 ° S 18.366222 ° E ﻿ / - 33.806734; 18.366222 Coordinates: 33 ° 48 ′ 24" S 18 ° 21 ′ 58" E ﻿ / ﻿ 33.806734 ° S 18.366222 ° E ﻿ / - 33.806734; 18.366222 </Td> </Tr> <Tr> <Th> Country </Th> <Td> South Africa </Td> </Tr> <Tr> <Th> Province </Th> <Td> Western Cape </Td> </Tr> <Tr> <Th> Municipality </Th> <Td> City of Cape Town </Td> </Tr> <Tr> <Th_colspan="2"> Area </Th> </Tr> <Tr> <Th> Total </Th> <Td> 5.18 km (2.00 sq mi) </Td> </Tr> <Tr> <Th_colspan="2"> Population (2011) </Th> </Tr> <Tr> <Th> Total </Th> <Td> 116 </Td> </Tr> <Tr> <Th> Density </Th> <Td> 22 / km (58 / sq mi) </Td> </Tr> <Tr> <Th_colspan="2"> Racial makeup (2011) </Th> </Tr> <Tr> <Th> Black African </Th> <Td> 60.3% </Td> </Tr> <Tr> <Th> Coloured </Th> <Td> 23.3% </Td> </Tr> <Tr> <Th> White </Th> <Td> 13.8% </Td> </Tr> <Tr> <Th> Other </Th> <Td> 2.6% </Td> </Tr> <Tr> <Th_colspan="2"> First languages (2011) </Th> </Tr> <Tr> <Th> Xhosa </Th> <Td> 37.9% </Td> </Tr> <Tr> <Th> Afrikaans </Th> <Td> 35.3% </Td> </Tr> <Tr> <Th> Zulu </Th> <Td> 15.5% </Td> </Tr> <Tr> <Th> English </Th> <Td> 7.8% </Td> </Tr> <Tr> <Th> Other </Th> <Td> 3.4% </Td> </Tr> <Tr> <Th> PO box </Th> <Td> 7400 </Td> </Tr> <Tr> <Td_colspan="2"> </Td> </Tr> <Tr> <Th_colspan="2"> UNESCO World Heritage Site </Th> </Tr> <Tr> <Th> Type </Th> <Td> Cultural </Td> </Tr> <Tr> <Th> Criteria </Th> <Td> iii, vi </Td> </Tr> <Tr> <Th> Designated </Th> <Td> 1999 (23rd session) </Td> </Tr> <Tr> <Th> Reference no . </Th> <Td> 916 </Td> </Tr> <Tr> <Th> State Party </Th> <Td> South Africa </Td> </Tr> <Tr> <Th> Region </Th> <Td> Africa </Td> </Tr> <Tr> <Th_colspan="2"> </Th> </Tr> <Tr> <Td_colspan="2"> </Td> </Tr> </Table> <Tr> <Th_colspan="2"> Robben Island Robbeneiland </Th> </Tr>

When did robben island became a world heritage site