Nearly 8,000 visitors were expected to take high-speed elevators up to the observation decks of the 634-meter tower to mark its opening. Some reportedly waited in line more than a week to get the coveted tickets for a panoramic view, though Tuesday ended up being cloudy in Tokyo.

Skytree is recognized by Guinness World Records as the tallest tower, beating out the Canton Tower in China, which is 600 meters.

The world's tallest structure is Dubai's Burj Khalifa, which stands 828 meters. That's in a different category because it's a skyscraper, not a tower.

The Skytree will serve as a broadcast tower for television and radio, along with being a tourist attraction. It replaces the 333-meter-tall Tokyo Tower - a symbol of Japan's capital since 1958 - as the broadcast hub.