Norwegian Hydro-Electric Administration building, Oslo, Norway (circa 1967)

Designed by Lykke and Knut Enger, this office building is an outstanding example of the use of Naturbetong, an application of concrete that is more or less specific to Norway. Naturbetong involves briefly placing selected coarse aggregates in to the concrete forms during construction, injecting a grout to fill the interstices, and then sandblasting the surfaces soon after removing the forms, leaving an even, textured concrete surface.

The office building utilises this application both externally and internally, covering every external concrete element as well as internal features such as columns and balustrades.