Optoppen : adding rooftop housing to postwar apartment buildingsFlexible housing extension in wood frame constructionBuilding in prime locations : topping out with steel frame constructionAir-bound building : building on a raised ground levelUpper city changes the horizon : a new look at the rooftop landscapeUpper city : discovering and making the layered cityTopping up in WinschotenLightly densified : groundbreaking ideas for uplifting downtown Rotterdam : seven multidisciplinary design teams make Rotterdam rise above itselfWhat does your porch apartment weigh? : densification potential of porch flats South Holland construction year '45-'65