Hejduk drew Wall House II in 1973 for A.E. Bye, a landscape architect and fellow faculty member at Cooper Union, who wanted a residence in Ridgefield, Connecticut. The wooded site made construction expensive. Bye walked away. Hejduk shopped the design to other clients - no takers. Most architects would have shelved it. Hejduk kept drawing variations, treating the house less as a building than as a continuing argument about what walls do. He published it, taught from it, refused to let it stay a sketch. By the time Groningen came calling in 1990, Wall House II had spent seventeen years as one of the most famous unbuilt houses in modern architecture - a paper monument to a building that nobody had been willing to pay for.

The path from drawing to building ran through a city planning experiment with a wonderful name: Making the City Boundaries. Daniel Libeskind, himself a former student of Hejduk, drew a masterplan for Groningen that invited designers to mark the city's arterial roads with structures that would tell the story of the place. Niek Verdonk, Groningen's director of city planning, and Olof van de Wal of the architectural group Platform Gras took up the cause for Wall House II. They worked at it for eleven years. Eleven years of cost estimates, code negotiations, developer pitches, and the patient persuasion that civic architecture requires. Wilma BV Developers eventually agreed to build the house and sell it. The Berlin architect Thomas Muller, another Cooper Union alumnus, redrew the plans for Dutch building codes - which required, among other things, leaving space between the wall and the rooms for hand plastering.

The building is dominated by a single enormous wall, four organic-formed rooms clustered on one side, a long narrow corridor running along the other. Reinforced concrete for the wall and central column. Steel frame, wooden studs, and stucco for the corridor. The whole composition reads like a Cubist painting that learned to stand up. Hejduk thought walls were the most interesting thing in architecture because they exist to be crossed. "We're continuously going in and out, back and forth, and through them," he wrote. "A wall is the quickest, the thinnest, the element we're always transgressing." The wall heightens the sense of passage, he believed, while its thinness reduces every crossing to a momentary present. It is a peculiar idea to make into a 2,500-square-foot house, but that is what Wall House II is - a philosophical proposition you can live inside.

The colors came from Paris. Hejduk had visited Le Corbusier's La Roche House and changed his mind about what color could do. "After that experience, I could never do another white or primary-colored house," he said. The La Roche colors were "hardly apparent at first, but after you were there awhile you saw not only that they changed constantly, but that they were delicate and muted, and also saturated at the same time." Wall House II in Groningen sits on the Hoornse Meer with a view across the Paterwoldse Meer, its bright pinks and yellows and greens reading at first like a child's toy left by the water. Stay longer and the colors do exactly what Hejduk learned from Le Corbusier - they shift, soften, deepen, and resist being looked at all at once.

The total construction cost was $600,000. It was sold as a private residence with one condition written into the deed: the public can visit it one month per year. Someone lives here the other eleven months. They cook, sleep, host friends, and presumably field occasional questions from strangers who have come to see a house that an American architect drew for Connecticut and a Dutch city built without him. Hejduk left a thin catalog of realized work and a vast catalog of beautiful unbuilt projects. Wall House II is the rare drawing that crossed the wall - from paper to concrete, from idea to address, from architect's mind to a place where someone gets the mail.