In the late 1800s, unscrupulous slumlords took advantage of the Chicago's lax enforcement of housing construction codes to build sub-standard and crowded housing on small lots near the factories and stockyards that employed the waves of European immigrants moving into Chicago. This 1901 study attempted to raise public awareness of the devastating living conditions in some of the worst wards of the city. It paid particular attention to the "double-decker" or "dumb-bell" buildings where front and rear tenement buildings were joined by narrow passageways without proper provision for ventilation and light. "Some apartments have no windows opening upon any other space. The sun reaches the bottom for a few moments only each day, and the lower rooms opening upon it are always dark."