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Mexico City is turning the airport experience into something so pleasant you might even want to hang out there while waiting for a flight.

When redesigning an airport that officials expect will service 50 million people per year, architects focused on good lighting, sustainable design and efficiency. The new building will be made of glass and steel, with a soaring roof that will incorporate solar technology that helps power the entire airport.

The airport will also collect rainwater, which it will treat and recycle, and will have its own on-site energy plant. With the goal of being the world's most sustainable airport, it may also be the most traveler-friendly: The roof will be designed for optimal viewing of planes circling overhead, and all the gates will be within walking distance.

Construction will be in two phases, with completion estimated for 2020. --J.E.