The Gemeentemuseum in The Hague has the largest collection of Mondrians in the world, and one of the largest collections of art and furniture from the broader de Stijl movement. Hometown favorites, I guess.
Anyway, this boys bedroom design just caught my eye. Vilmos Huszar designed the color schemes in 1918 for the Bruynzeel family, with furniture by Gerrit Rietveld's lesser known mentor Piet Klaarhamer. It holds up.