Haus Gross in Greifensee, Switzerland, looks like a typical house by all accounts. But this modern and inventive design proves that looks can be deceiving. This understated, low-profile house holds a buried treasure in the form of an underground living space. The 721-sq.-ft. sub-grade home addition includes two sunken open-air courtyards leading into the three children’s bedrooms, a bathroom and a state-of-the-art home theater for private film screenings. A two-storey glazed façade lets light flood every corner, above ground and below.