Keret House

The Keret House measures 92 centimeters at its narrowest and 152 at its widest, making it probably the narrowest inhabitable house in the world. Polish architect Jakub Szczesny wedged the three-story steel structure in 2012 into a gap between a 1930s prewar block and a postwar building on Chlodna Street in Wola - exactly where the wall between the small and large Warsaw ghettos once ran. The house is named after Israeli writer Etgar Keret, its first resident; since then it has served as a writers' residence administered by the Polish Modern Art Museum. The interior fits a bed, desk, microwave and bathroom - the stairs are just a ladder. Visits are by appointment only; from outside the striking white-clad sliver is visible straight from the street.