Cairo is one of the most densely populated in the world, with only one footprint of green space per person prior to 2005. His Highness the Aga Khan, the spiritual leader of the Shia Imami Ismaili Muslims, saw the need to relieve this congestion. The result is Al-Azhar Park: a 500-year-old dump-turned-"urban lung" that provides much-needed green space and a source of civic pride.