Much of the building will be open to the public

Sir Norman has called it: "A building that you can look at from the outside and see inside."

It has no front or back with its shape being taken from a modified sphere - its shape has been likened to a car headlight or a glass testicle.

But the shape has been used to minimise the surface area exposed to direct sunlight.

It is part of a greener outlook in architecture.

Public piazza

Less heat can escape from the altered sphere than would escape from conventional office blocks.

Mr Livingstone has described the building as "one of the most spectacular examples of architecture to be seen in the capital for years."

There will be 185,000 square-feet of flexible office space as well as the assembly chamber, committee rooms and public facilities.

A piazza at the base of the building will look across the river with public areas landscaped with seating, water features and trees.

More London

There will be a cafeteria, display space, a library and other public facilities on the lower floors of the building.

Builders Arup and Partners began work in 1999 on the �43m project.

The GLA has taken it on a 25-year lease.

It is part of the More London development which will create 2.5 million square-feet of office space across the river from the Tower of London.

A mirrored public exhibition room has been built

The spiral staircase looks like a peeled orange

There are spectacular views from the tenth floor

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