The exploration of the Grave Circle within the Cyclopean Walls near the Lion Gate, which we began in 1920, resulted in the discovery or identification of several groups of graves, which led us to the conclusion that a Prehistoric Cemetery had lain on the hillside at this point before the fortifications were constructed and that the Shaft Graves were a group of royal graves enclosed within that cemetery.

In 1939, following a suggestion made by Tsountas, we explored the area to the north-west of the Lion Gate outside the walls and found there fifteen graves belonging to the Prehistoric Cemetery which was in use from Middle Helladic to Late Helladic II times. Subsequent exploration outside the walls in this region has resulted in the discovery of yet more graves, and those so far noted and explored outside the walls now number forty. To these we should probably add one more, a disturbed grave found recently by the Anastelosis Section of the Greek Archaeological Service in its operations at the north-west angle of the bastion on the west of the entrance to the Lion Gate.