BT Tower

The BT Tower is a grade II listed communications tower located in Fitzrovia, London, owned by BT group. It has been previously known as the GPO Tower, the Post Office Tower, and the BT Tower. The main structure is 177 metres (581 ft) high, with a further section of aerial rigging bringing the total height to 189 metres (620 ft). Its Post Office code was YTOW.
Upon completion in 1964, it overtook the Milbank Tower to become the tallest building in both London and the United Kingdom, titles that it held until 1980