Sirikwa holes are saucer-shaped hollows found on hillsides in the western highlands of Kenya[1] and in the elevated stretch of the central Rift Valley around Nakuru.[2] These hollows, each having a diameter of 10–20 metres and an average depth of 2.4 metres, occur in groups, sometimes numbering fewer than ten and at times more than a hundred. Archaeologists believe that construction of these features may have begun in the Iron Age.[3][4]