Like colored taffy, strips of the interior concrete floor of Milwaukee's new Midwest Express Convention Center slip under the windows of the building's exterior facade and pass to the outside, where they roll through the gray concrete sidewalk and curl to form flamboyant bus-stop shelters or benches. While these ribbons of interior colored concrete slip outside, some of the gray exterior sidewalk makes its way inside, with some strips flowing through the terra-cotta colored concourse floor and into the atrium below to form seating.

New York artist Vito Acconci is the creator of "Walkways Through the Wall" and one of several artists who helped design the convention center. Laying out these ribbons of concrete took great care and precision. "We laid out the whole job completely before pouring concrete," says Joel Becker of Hunzinger Construction, Brookfield, Wis., the exterior concrete flatwork contractor. "We strung lines in various directions to make sure it'd work. We had to make sure before we poured concrete that all the lines intersected where they were supposed to."