The Keret House is officially the world's narrowest house, squeezed into a gap between two buildings in the Muranów neighbourhood. At its narrowest it is 92 centimetres wide; at its widest, 152 centimetres. The building was designed by architect Jakub Szczęsny in 2012 as an art space for Israeli author Etgar Keret, who was invited to be its first resident — a reference to the fact that Keret's family survived the Warsaw Ghetto, which occupied this very neighbourhood.
The house has a kitchen, bathroom, study, and sleeping area stacked across five levels, all accessible by a fold-down ladder. It functions as an artist-in-residence space rather than a permanent home. You can't enter it, but you can photograph it from the street and contemplate the life choices required to live there.