The urban legend about cities of homeless living underground in the neglected corridors of New York City's subways was partly true. For about a decade in the 80s, a colony of extremely resourceful hobos built shelters in an underground section of Penn-Central railroad beneath New York. They had stolen electricity and a few even had cold running water; many worked outside as can collectors or street vendors, and rifled garbage for uneaten restaurant food. The routines of these underground inhabitants, and their squabbles with each other, were recorded in a pretty good documentary called Dark Days available from Amazon or Netflix. The film records their fight with the city to keep their plywood homes, filled with TVs, beds, and mini--kitchens. These shelters were quite sophisticated and great examples of street use of scrounged materials.