There are 47 buildings and structures in Tokyo that stand taller than 180 metres (591 ft). Tokyo is the most populated of Japan's 47 prefectures. The tallest structure in the prefecture is Tokyo Sky Tree, a lattice tower that rises 634 metres (2,080 ft), which will open to the public on 22 May 2012. It also stands as the tallest structure in Japan, the tallest tower in the world and the second-tallest freestanding structure in the world. The tallest building and third-tallest overall structure in Tokyo is the 248-metre-tall (814 ft) Midtown Tower, which was completed in 2007. The prefecture's second tallest building is the Tokyo Metropolitan Government Building, which rises 48 stories and 243 metres (797 ft) in height. Overall, of the 25 tallest buildings and structures in Japan, 17 are in Tokyo. Skyscrapers are a relatively recent phenomenon in Japan. Due to aesthetic and engineering concerns, Japan's Building Standard Law set an absolute height limit of 31 metres until 1963, when the limit was abolished in favor of a Floor Area Ratio limit. (Full list...)