There is no general consensus on the height or number of storeys above which buildings should be classified as tall buildings or skyscrapers. The architectural/ structural height of a building is measured from the open-air pedestrian entrance to the top of the building, ignoring antennae and flagpoles. According to the CTBUH1 (Council on Tall Buildings and Urban Habitat), buildings of 14 storeys or 50 metres’ height and above could be considered as “tall buildings”; buildings of 300 metres’ and 600 metres’ height and above are classified as “supertall buildings” and “megatall buildings” respectively. The CTBUH measures the “height to architectural top” from the level of the lowest “significant open-air pedestrian entrance” to the architectural top of the building, including spires, but not including antennae, signage, flag poles or other functional-technical equipment. In this book, this height measurement is used for the “architectural height” of the buildings.