<Tr> <Td> Theopetra cave </Td> <Td> </Td> <Td> Greece </Td> <Td> 21000 BC </Td> <Td> Stone wall </Td> <Td> The oldest known human - made structure . <P> The structure is a stone wall that blocked two - thirds of the entrance to the Theopetra cave near Kalambaka on the north edge of the Thessalian plain . It was constructed 23,000 years ago, probably as a barrier to cold winds . </P> </Td> </Tr> <P> The structure is a stone wall that blocked two - thirds of the entrance to the Theopetra cave near Kalambaka on the north edge of the Thessalian plain . It was constructed 23,000 years ago, probably as a barrier to cold winds . </P> <Tr> <Td> Göbekli Tepe </Td> <Td> </Td> <Td> Turkey </Td> <Td> 9500--8400 BC </Td> <Td> Ceremonial </Td> <Td> The oldest known human - made religious structure . </Td> </Tr> <Tr> <Td> Zealots of Jericho </Td> <Td> </Td> <Td> Palestinian territories </Td> <Td> 8000 BC </Td> <Td> Defensive / agricultural </Td> <Td> See also Wall of Jericho . </Td> </Tr>

Where is the oldest castle in the world located