This 900-tonne tower designed by the Richard Rogers Partnership was the subject of a dramatic feat of engineering last week when airport operator BAA moved it almost 2 km across the runways at Heathrow Airport. The conical structure will form the top section of the traffic control centre. It was transported with the aid of a specially designed steel frame, attached to its base to lower the centre of gravity, which stabilised the structure. The engineers are Arup and Dorman Long. Mace handled construction management.