"In situ" literally means “in place” or “in position.” 

From a landscape design perspective it extends the definition to explore the intervention between landscape and the built environment.  This is my third visit to the MOMA exhibit “IN SITU” which explores this burgeoning discussion between the built and natural environment which began thru books such as Ian McHarg’ Design With Nature (available for your kindle!) and has culminated recently with Charles Waldheim’s Landscape Urbanism Reader.  The exhibit showcases flat art drawings in addition to the models below of works by James Wines, Toyo Ito, Tadao Ando and Bernard Tschumi.