Definition of building site:
(n) :
(construction) The site, the place where a building is located, is currently under construction, or shall be constructed (including structures other than buildings).
(n) :
(archaeology) The site of a former structure, indicated by an assemblage of features, artifacts or debris, remote-sensing data, or historic records (e.g., deed records).
(n) :
(figuratively) A messy, disorganized area.