Tokyo Skytree (東京スカイツリー, Tōkyō Sukaitsurī; [toːkʲoː sɯ̥kaitsɯriː] ), a.k.a Tokyo Sky Tree, is a broadcasting and observation tower, located in Sumida, Tokyo, Japan. It has been the tallest tower in Japan since opening in 2012, and reached its full height of 634 metres (2,080 feet) in early 2011, making it the tallest tower in the world, displacing the Canton Tower, and the third tallest structure in the world behind Merdeka 118 (678.9 metres or 2,227 feet) and Burj Khalifa (829.8 m or 2,722 ft).
The tower is the primary television and radio broadcast site for the Kantō region; the older Tokyo Tower no longer gives complete digital terrestrial television broadcasting coverage because it is surrounded by high-rise buildings. Skytree was completed on Leap Day, 29 February 2012, with the tower opening to the public on 22 May 2012. The tower is the centerpiece of a large commercial development funded by Tobu Railway (which owns the complex) and a group of six terrestrial broadcasters headed by NHK. Trains stop at the adjacent Tokyo Skytree Station and nearby Oshiage Station. The complex is seven kilometres (4.3 miles) northeast of Tokyo Station. Sumida Aquarium is in the Tokyo Solamachi complex.
The tower's design was published on 24 November 2006, based on the following three concepts:
Fusion of neofuturistic design and the traditional beauty of Japan
Catalyst for revitalization of the city
Contribution to disaster prevention – "Safety and Security"
The base of the tower has a structure similar to a tripod; from a height of about 350 m (1,150 ft) and above, the tower's structure is cylindrical to offer panoramic views of the river and the city. There are observatories at 350 m (1,150 ft), with a capacity of up to 2,000 people, and 450 m (1,480 ft), with a capacity of 900 people. The upper observatory features a spiral, glass-covered skywalk in which visitors ascend the last 5 m (16 ft) to the highest point at the upper platform. A section of glass flooring gives visitors a direct downward view of the streets below.
The tower has seismic proofing, including a central shaft made of reinforced concrete. The main internal pillar is attached to the outer tower structure for the first 125 m (410 ft) above ground. From there until 375 m (1,230 ft), the pillar is attached to the tower frame with oil dampers, which act as cushions during an earthquake. Additional resilience is achieved through an "added mass control mechanism" (or tuned mass damper) – a damping system which, in the event of an earthquake, moves out of step with the building's structure, to keep the center of gravity as central as possible to the tower's base. According to the designers, the dampers can absorb 50 percent of the energy from an earthquake.
The exterior lattice is painted a color officially called "Skytree White". This is an original color based on a bluish-white traditional Japanese color called aijiro (藍白).
The illumination design was published on 16 October 2009. Two illumination patterns alternate daily. One is the sky blue Iki (chic, stylish), and the other is the purple Miyabi (elegance, refinement). The tower is illuminated using LEDs.
From October to November 2007, suggestions were collected from the general public for the name to be given to the tower. On 19 March 2008, a committee chose six final candidate names: Tōkyō Sukaitsurī (東京スカイツリー; "Tokyo sky tree"), Tōkyō Edo Tawā (東京EDOタワー; "Tokyo Edo tower"), Raijingu Tawā (ライジングタワー; "Rising tower"), Mirai Tawā (みらいタワー; "Tower of the future"), Yumemi Yagura (ゆめみやぐら; "Dream lookout"), Raijingu Īsuto Tawā (ライジングイーストタワー; "Rising east tower"). The official name was decided in a nationwide vote, and was announced on 10 June 2008 as "Tokyo Skytree". The name received around 33,000 votes (30%) out of 110,000 cast, with the second most popular name being "Tokyo Edo Tower".
The height of 634 m (2,080 ft) was selected to be easily remembered based on numeric substitution. The figures 6 (mu), 3 (sa), 4 (shi) stand for "Musashi", an old name for the region where the Tokyo Skytree stands.
Tokyo Skytree is used as a radio/television broadcast and communications tower.
14 July 2008: A ceremony was held at the site to mark the start of construction.
6 April 2009: The foundations for the three main legs were completed.
7 August 2009: The tower reached a height of 100 m.
16 October 2009: The projected height was increased from 610 to 634 m (2,001 to 2,080 ft) to make it the highest self-supporting steel tower. Also, 6-3-4 is Mu-sa-shi in Japanese wordplay goroawase.
10 November 2009: The tower reached a height of 200 m.