The designer of the Zig Zag-chair is also the designer of what UNESCO World Heritage Site?
Zig-Zag Chair: The Zig Zag-chair is a chair designed by Gerrit Rietveld in 1934. Gerrit Rietveld:  One of the principal members of the Dutch artistic movement called De Stijl, Rietveld is famous for his Red and Blue Chair and for the Rietveld Schröder House, which is a UNESCO World Heritage Site.
Rietveld Schröder House