11 reading areas with 1,200 seats

The building will house 12 million books which are currently scattered over 20 sites in London and store them in proper conditions.

It has 300 kilometres of underground shelving. The Humanities Reading Room, which opens today, is the first of 11 reading areas with 1,200 seats.

But the project has been dogged by controversy. It has cost more than �500m, three times the original estimate.

Millions of books are being moved to new library

The building work has been plagued by mistakes, delays and constant changes to the design.

Its design, by the architect Colin St John Wilson, has been criticised by others, with Prince Charles once likening it to an academy for secret policemen.

Regular users have regretted the library's departure from the historic Round Reading Reading Room at the British Museum which closed last month.

Some are already warning about the high running costs of the new building.

The library says its Government grant is too small and it may have to introduce charges for readers, or buy fewer books.