30 St Mary Axe nearly oblivious to the tower's existence until directly underneath it. The building was constructed by Skanska, completed in December 2003 and opened on 28 April 2004. The primary occupant of the building is Swiss Re, a global reinsurance company, which had the building commissioned as the head office for its UK operation. The tower is thus sometimes known as the Swiss Re Building, although this name has never been official and has more recently fallen out of favour, since the company's main headquarters is in Zurich and the Gherkin name has become more popular. The building uses energy-saving methods which
30 St Mary Axe than the old Exchange on the site. The site was special because it needed development, it was not on any of the "sight lines" (planning guidance requires that new buildings do not obstruct or detract from the view of St Paul's dome when viewed from a number of locations around London), and it had housed the Baltic Exchange. The plan for the site was to reconstruct the Baltic Exchange. GMW Architects proposed a new rectangular building surrounding a restored exchange: it would have the type of large floor plan that banks liked. Eventually, the planners realised that the exchange was