ABSTRACT
Being always at the mercy of a new discovery, we shall never know for sure when the first retaining wall was constructed. As soon as man became sedentary, in fact, which was towards the end of the tenth millennium B.C., he set about building defences by raising obstacles that were difficult to climb.These defensive constructions were followed by monuments with a religious purpose inspired by the myth of the ascension towards the heavens. It would appear that the first examples of the idea of providing a vertical support for a mass of materials are to be found among the megalithic monuments on the Atlantic coast of Europe: a typical example is the Newgrange Cairn in Ireland, erected in the fourth millennium B.C. (Refs. 1 - 3). It was shaped like a drum with a diameter of 82 m (Fig. 1) and vertical sides of 4.20 m high formed of upright raised stones planted side by side in the earth up to a height of 1.20 m and surmounted by a masonry without mortar. This retaining structure enclosed a mass of rounded stones taken from the bed of a nearby river and resisted for just over 500 years
