The BT Centre is the global headquarters and registered office of BT Group, located in a 10-storey office building at 81 Newgate Street, London EC1A 7AJ, opposite St. Paul's tube station. It should not be confused with the much more prominent BT Tower. A plaque on the outside of the building marks this as the location from which Guglielmo Marconi made the first public transmission of wireless signals, in 1897 whilst it was the Telegraph Office building of the General Post Office complex More information on the Wikipedia page [1]