The Rooftop Homes of Cairo's Racing Pigeons

Gaze across the Cairo skyline and your eyes might hit stilted, rickety structures precariously perched on rooftops. Looking like horrible POW cages, these are in fact nest boxes for pigeons that've been trained to fly around the city in large, sky-darkening squadrons.

This feathery facet of Egyptian culture served as the inspiration for a great new photography series by Manuel Alvarez Diestro, the same guy who soulfully documented Hong Kong's super-dense cemeteries. The 42-year-old photographer traveled from his London home to Cairo during and after the 2011 revolution to work in some of the city's poorer neighborhoods. His focus was the zabbaleen, a disadvantaged community of garbage people (literal translation) whose duty it is to collect and sort through rubbish, much like Brazil's trash mountain-climbing catadores.