Abstract: A standard construction unit is provided by a monolithic precast reinforced concrete panel which has a generally rectangular peripheral configuration. A pair of flanges project from and extend longitudinally along the opposite sides of one face thereof to provide the unit with a shallow U-shaped cross-section. Connector elements are embedded within the other face of the panel adjacent its sides to permit connection of it to adjacent like panels. Door or window openings may be provided in the web portion.A building structure is supported on a footing and has walls, a roof and, optionally, a floor formed from the standard panels. The walls are formed by a plurality of the panels disposed vertically in side-by-side relationship and connected to each other by side fastener means bridging the panels and engaged with the connector elements and, at their lowermost ends, to the footing.