<Table> <Tr> <Th_colspan="2"> Great Wall of China </Th> </Tr> <Tr> <Td_colspan="2"> 萬里 長城 </Td> </Tr> <Tr> <Td_colspan="2"> The Great Wall of China at Jinshanling </Td> </Tr> <Tr> <Td_colspan="2"> Map of all the wall constructions </Td> </Tr> <Tr> <Th_colspan="2"> General information </Th> </Tr> <Tr> <Th> Type </Th> <Td> Fortification </Td> </Tr> <Tr> <Th> Country </Th> <Td> China </Td> </Tr> <Tr> <Th> Coordinates </Th> <Td> 40 ° 41 ′ N 117 ° 14 ′ E ﻿ / ﻿ 40.68 ° N 117.23 ° E ﻿ / 40.68; 117.23 Coordinates: 40 ° 41 ′ N 117 ° 14 ′ E ﻿ / ﻿ 40.68 ° N 117.23 ° E ﻿ / 40.68; 117.23 </Td> </Tr> <Tr> <Th_colspan="2"> Technical details </Th> </Tr> <Tr> <Th> Size </Th> <Td> 21,196 km (13,171 mi) </Td> </Tr> <Tr> <Th_colspan="2"> </Th> </Tr> <Tr> <Th_colspan="2"> UNESCO World Heritage Site </Th> </Tr> <Tr> <Th> Criteria </Th> <Td> Cultural: (i), (ii), (iii), (iv), (vi) </Td> </Tr> <Tr> <Th> Reference </Th> <Td> 438 </Td> </Tr> <Tr> <Th> Inscription </Th> <Td> 1987 (11th Session) </Td> </Tr> <Tr> <Td_colspan="2"> (edit on Wikidata) </Td> </Tr> <Tr> <Th_colspan="2"> </Th> </Tr> </Table> <Tr> <Th_colspan="2"> Great Wall of China </Th> </Tr>

When did the great wall became a world heritage site