Mexico City is sinking nearly 10 inches every year, making it one of the world’s fastest-sinking metropolitan areas. That’s according to newly released satellite imagery from NASA. The sprawling megalopolis with a population of some 22 million was built upon an ancient lake bed. Over the decades groundwater pumping and urban development have dramatically shrunk the aquifer. So Mexico City has been sinking for over a century, leaving many monuments and older buildings visibly tilted to the side. In some parts the drop is coming at an average rate of 0.78 inches a month.