7 January 2011
Last updated at 12:34
The United Nations headquarters in New York is undergoing a massive refurbishment programme costing $1.9bn (£1.23bn). The Capital Master Plan (CMP) is expected to be completed by 2013.
The main Secretariat building is being updated to meet modern architectural standards: blast-proof glass is being installed for the first time.
Construction on the UN headquarters began in 1950 and covers 17 acres in midtown Manhattan alongside the East River.
It was designed by a team of architects including Le Corbusier from France and the Brazilian, Oscar Niemeyer.
The building was designed with all the needs of the UN’s diplomatic community in mind, including a barbershop on the 20th floor with a view of the Empire State Building (far left of window). The barbers closed in the early 1980s.
In 1951, the UN offices had all the latest technology, including air conditioning.
Much of the internal infrastructure has become obsolete, including this pneumatic messaging system which linked the Secretariat building with the General Assembly, press room and other areas.
A large part of the original infrastructure, including 90 miles of pipework, is now being replaced.
The sculpture, Mother and Child, by the Italian artist, Giacomo Manzu, has been moved to another part of the headquarters.
Up to 6,000 UN staff have been relocated. Many, including Secretary General Ban Ki-moon himself, are working in the temporary North Lawn Building next to the General Assembly.
The exterior of the building will remain the same: a landmark on the iconic New York City skyline.