The Canary Wharf Tower is currently the tallest office building with a height of 244 metres in the United Kingdom. The architects chosen for the building were Cesar Pelli & Associates, Adamson Associates, and Frederick Gibberd Coombes & Partners. Construction on the tower began in 1988 and it was open for business in August 1991. Construction was given to Sir Robert McAlpine & Sons in association with Ellis Don of Toronto. The Canary Wharf Tower is similar in design to Three World Financial Center, New York City, which are designed by Cesar Pelli, too. The ground floor, foyer area and basement levels of it are open to the general public, having an underground shopping area and a transport interchange, but the tower has got currently no public observation floor.