Mexico may be known for Tequila and Tacos, but it's also home to the largest open air salt mine in the world, extracting 7.5 million tons of salt each year. We'll visit this giant above ground mine that's been created by tidal sea water coming onto the land and being evaporated into the sun. Huge dykes are used to create salt pans that trap the sea water. These man-made salt pans cover over 180 sq km. MegaWorld will go to new heights as the world's tallest cable bridge is being built as part of a $1.2 billion, 230 km construction project that runs from the Mexican interior to the pacific coast. At 390 m (1280 feet), the Baluarte Bridge will be the highest bridge in North America and the highest cable stayed bridge in the world. And we'll find out how a 62-kilometer tunnel might be the key to preventing Mexico City from sinking.