The linear hole that is dug to provide a solid footing for a wall. Such trenches are as wide as the wall will eventually be and are usually excavated to the point where a solid and stable substrate exists. The full width of the trench is then typically filled with a rubble footing onto the centre of which the wall is set. Once the construction of the wall has taken it above ground level the open parts of the construction trench on either side are backfilled, often with building debris and rubbish from the general vicinity. Such trenches are important to identify in archaeological excavations because they show the level within the stratigraphy at which construction of a wall or structure began. Also known as a foundation trench or a bedding trench. See also robber trench.