The Tokyo Skytree (Tōkyō Sukaitsurī) became the tallest building in Japan when it opened in 2012 and is the second-tallest building in the world after the Burj Khalifa. Stretching 634 meters (2,080 feet) into the sky, the tower contains two observation decks, one at 350m up and the other at 450m, from which you can see all the way to Mount Fuji during good weather! Lines on the day can get long, so book skip-the-line tickets in advance for the best experience.