Dutch firm RAAAF (Rietveld Architecture-Art-Affordances), along with Atelier de Lyon, took the monolithic form of a concrete WWII bunker and revealed its insides by slicing the structure cleanly in half. Built to shelter up to 13 soldiers during bombing raids, the bunker is one of 700 constructed by the New Dutch Waterline (NDW), a military line of defense in use from 1815 until 1940. It took 40 days for a diamond wire saw to cut through the bunker and reveal the unusual spaces hidden inside. With the addition of a pathway that intersects its halves, “Bunker 599″ makes visible, accessible, and tangible a unique part of Dutch history. RAAAF will be one of over 60 architects taking part in the inaugural Chicago Architecture Biennial this fall.