In the living area, a 2010 Vertigo lamp by Constance Guisset hangs above a 1974 Gijs Bakker Strip table; the residents believe the floor lamp in the foreground is Murano glass. Dark panels of metal, left behind by the previous homeowners, were stored outside until a rich patina developed. Now they hide a library.  Photo 4 of 7 in Now That's How You Double Your Square Footage