<Table> <Tr> <Td> "</Td> <Td> Among the gold mines of the inland plains between the Limpopo and Zambezi rivers there is a fortress built of stones of marvelous size, and there appears to be no mortar joining them...This edifice is almost surrounded by hills, upon which are others resembling it in the fashioning of stone and the absence of mortar, and one of them is a tower more than 12 fathoms (22 m) high . The natives of the country call these edifices Symbaoe, which according to their language signifies court . </Td> <Td>" </Td> </Tr> </Table> <Tr> <Td> "</Td> <Td> Among the gold mines of the inland plains between the Limpopo and Zambezi rivers there is a fortress built of stones of marvelous size, and there appears to be no mortar joining them...This edifice is almost surrounded by hills, upon which are others resembling it in the fashioning of stone and the absence of mortar, and one of them is a tower more than 12 fathoms (22 m) high . The natives of the country call these edifices Symbaoe, which according to their language signifies court . </Td> <Td>" </Td> </Tr> <P> The ruins form three distinct architectural groups . They are known as the Hill Complex, the Valley Complex and the Great Enclosure . The Hill Complex is the oldest, and was occupied from the ninth to thirteenth centuries . The Great Enclosure was occupied from the thirteenth to fifteenth centuries, and the Valley Complex from the fourteenth to sixteenth centuries . Notable features of the Hill Complex include the Eastern Enclosure, in which it is thought the Zimbabwe Birds stood, a high balcony enclosure overlooking the Eastern Enclosure, and a huge boulder in a shape similar to that of the Zimbabwe Bird . The Great Enclosure is composed of an inner wall, encircling a series of structures and a younger outer wall . The Conical Tower, 5.5 m (18 ft) in diameter and 9 m (30 ft) high, was constructed between the two walls . The Valley Complex is divided into the Upper and Lower Valley Ruins, with different periods of occupation . </P> <P> There are different archaeological interpretations of these groupings . It has been suggested that the complexes represent the work of successive kings: some of the new rulers founded a new residence . The focus of power moved from the Hill Complex in the twelfth century, to the Great Enclosure, the Upper Valley and finally the Lower Valley in the early sixteenth century . The alternative "structuralist" interpretation holds that the different complexes had different functions: the Hill Complex as a temple, the Valley complex was for the citizens, and the Great Enclosure was used by the king . Structures that were more elaborate were probably built for the kings, although it has been argued that the dating of finds in the complexes does not support this interpretation . </P>

What feature is found in the hill complex of the great zimbabwe