London Memorial and Royal Albert Hall in Kensington. Nelson's Column is a nationally recognised monument in Trafalgar Square, one of the focal points of central London. Older buildings are mainly brick built, most commonly the yellow London stock brick or a warm orange-red variety, often decorated with carvings and white plaster mouldings. In the dense areas, most of the concentration is via medium- and high-rise buildings. London's skyscrapers, such as 30 St Mary Axe, Tower 42, the Broadgate Tower and One Canada Square, are mostly in the two financial districts, the City of London and Canary Wharf. High-rise development is restricted
30 St Mary Axe designed by Norman Foster and Arup Group. It was erected by Skanska; construction started in 2001. The building has become a recognisable feature of London, and it is one of the city's most widely recognised examples of contemporary architecture. The building stands on the former sites of the Baltic Exchange (24-28 St Mary Axe), which was the headquarters of a global marketplace for shipping freight contracts and also soft commodities, and the Chamber of Shipping (30-32 St Mary Axe). On 10 April 1992, the Provisional IRA detonated a bomb close to the Exchange, causing extensive damage to the historic building