Today we visit seven natural wonders of the world: Angel Falls in Venezuela, the tallest waterfall in the world; the Aurora Borealis or Northern Lights, colorful light displays in the night sky; Uluru in Australia, the world's largest monolith; Guilin in China, known for its dramatic peaks and clear waters; the Grand Canyon in the United States, over a mile deep and 277 miles long; the Great Barrier Reef in Australia, the world's largest coral reef stretching over 2,000 km; and Iguassu Falls on the border of Argentina, Brazil and Paraguay, consisting of 275 separate falls that are 3 km long and 60 m high.