By Thomas Lane
BBC News, New York
Each day guides at the United Nations lead hundreds of visitors through the iconic New York headquarters.
The UN's iconic New York HQ was opened in 1950
Tourists file down neat corridors lined with artwork from around the world. Most also get a glimpse of the historic General Assembly hall and Security Council chamber.
UN official Werner Schmidt conducts a very different kind of tour. He is the chief spokesman for the Capital Master Plan (CMP) - a renovation project that is projected to cost nearly $2bn (£1bn).
Mr Schmidt's private tour is meant to show why that money is needed.
Going with him through the bowels of the building is like voyaging back in time. The equipment he displays was all built in the 1950s. Maintenance signs advise people to call emergency numbers that are decades out of date.
Occasionally he points to an exposed pipe and tells you it is lined with "that miracle building material from the 50s - asbestos".
Much of the equipment was only meant to last for two decades at the most. A small museum is actually seeking one piece that is still in use. Engineers often have to improvise replacement parts for gadgets that are no longer made.
Elsewhere in the building, water from the nearby East River seeps through the walls. Puddles sometimes form on basement floors and it is not unusual to see buckets catching drips from leaking pumps.
Michael Adlerstein, the architect who oversees the CMP, says the building "cannot function much longer in its present state".
He also has another reason for hoisting the infrastructure into the modern world - it is currently vulnerable to explosives.
"There's a tremendous need to secure the building against terrorist acts," he told the BBC.
Despite the grand setting, many of the fittings are worse for wear
Achieving that will entail strengthening the structure, and replacing the ill-functioning fire sprinklers.
Heightening the building's blast resistance, however, is no easy task. A recent report says this is one reason the plan is already behind schedule and over budget.
Nor does it help that all 192 member states have to vote on the details. CMP officials jokingly compare it to having 192 landlords, and face continual criticism from many quarters. Just this week, a representative for Pakistan slammed senior managers for "a lack of responsibility".
Stung by similar criticisms, and worried by potential rises in building costs, Mr Adlerstein recently proposed speeding up the renovations. He now hopes to get the work finished by 2013, three years earlier than originally envisaged.
The idea has the support of the Secretary General, Ban Ki-moon, who also has his own hopes for the project. Currently, the headquarters' annual heating and electric bill costs nearly $15m.
At Mr Ban's urging, project planners are trying to reduce energy consumption by 40%. He wants it to be a lesson for the world in how to "green" a building.
When the project is completed Mr Adlerstein says the building will look "exactly the same as when the ribbon was cut" in 1950.
Inside, however, officials hope maintenance will be cheaper, the functions will be greener, and tourists and diplomats alike will be considerably safer.