Hello how may I help you? What is the tallest building in Chicago? The Willis Tower, formerly the Sears Tower, is the tallest building in Chicago. Thank you, where is the tallest waterfall Angel Falls is the world's tallest waterfall in Venezuela. Where is the tallest indoor waterfall? Gardens by the Bay is the world's tallest indoor waterfall in Signapore. What is the fastest fish? The Sailfish is the world's fastest fish in the ocean. What is the longest living animal? The Queen Quahog is the world's longest living animal.