Polish builders work at the construction site of what they believe to be a contender for the title of the world's thinnest house, in Warsaw September 5, 2012. Polish builders on Wednesday began work on the 122 cm (48 inch) wide house. The house, which has three floors and will include a living space, a bathroom and a bedroom, will be squeezed into the gap between two buildings in the centre of the Polish capital, Warsaw. REUTERS/Peter Andrews (POLAND - Tags: BUSINESS CONSTRUCTION SOCIETY)