sentences:  Completed in 2005, the tower has twin concrete legs meeting at half height to form a single column from which steel sails are mounted; an observation deck at the top provides a view of the city and harbour for tourists.In late 2004, the Tricorn Centre, dubbed "The ugliest building in the UK" was finally demolished after years of delay and wrangling over the cost of doing so, and controversy as to whether it was worth preserving as an example of 1960s Brutalist architecture.In 2005, Portsmouth was a focus for "Sea Britain", a series of events to mark the 200th anniversary (bicentenary) of Lord Nelson's victory at the Battle of Trafalgar.