Old Palace Period
During an early or middle phase of this period a small, open-air sanctuary was established on the rocky ridge that rises in the middle of the southern side of the valley. This ridge overlooks the route that connects the wider region of Zakros to the coastal plain extending to its south. Thus, the establishment of the cult may imply an increased use of this route. It may also indicate an increasing exploitation, if not habitation of the valley.
The sanctuary was abandoned by the late Old Palace period. At that time, an imposing building of megalithic masonry was constructed on the ridge. This building is interpreted as a guard house. The radical change of function (religious to secular) within the same period is rather unusual, since the memory of cult places normally lives long after their desertion, discouraging the development of other uses.
The dam that blocked the upper part of the streambed at the southeast end of the valley may also be dated to this phase, if not to the beginning of the New Palace period.
The scattered pottery of the late Old Palace period indicates that the larger part of the valley was by then under exploitation.