Imbabah, Egypt

With a population of over 625,000, Imbaba is one of the most densely packed cities on the planet. This working-class neighborhood in northern Giza is a far cry from the picturesque Nile views tourists flock to - it's a crowded, chaotic urban sprawl where navigating the relentless bureaucracy is a persistent headache. Pigeon breeding may be a popular pastime for some residents, but the area has also seen its share of unrest, with the government deploying over 12,000 security forces to quash an "Emirate of Imbaba" declared by Islamic militants in the 1990s. For those seeking an authentic, if challenging, Egyptian experience, Imbaba may have some appeal, but it's certainly not for the faint of heart.