Unlike most buildings in Copenhagen, Polish artist Izabela Boloz's "Shadow City" disappears by night. Set on a bank in the neighborhood of Østerbro, this mercurial little city is made from 52 stencil-like cut-outs that cast shadows across 328 feet. Boloz, who's all about playing with shadow casting, explains that the two-dimensional "history of Copenhagen"—which features windmills, castles, and skyscrapers, to name a few—stems from an interest in the passing of time, which stretches and expands the architecture of her city with every hour. The effect is meant to surprise and intrigue city dwellers slogging along on their way to work, and is part of a collaboration with Metro Copenhagen to bring more art to public spaces in Copenhagen. Check out all the shots, plus a video, over on URDesign.