I ... (visit) three natural history museums so far.

Both a research institution and a fabulous museum, the NHM opened in Alfred Waterhouses purpose-built Romanesque palazzo on the Cromwell Road in 1881. Now joined by the splendid Darwin Centre extension, the original building still looks quite magnificent. The pale blue and terracotta faade just about prepares you for the natural wonders within.

Taking up the full length of the vast entrance hall is the cast of a Diplodocus skeleton. A left turn leads into the west wing or Blue Zone, where long queues form to see animatronic dinosaurs- especially endlessly popular T rex. A display on biology features an illuminated, man-sized model of a foetus in the womb along with graphic diagrams of how it might have got there.

A right turn from the central hall leads past the Creepy Crawlies exhibition to the Green Zone. Stars include a cross-section through a Giant Sequoia tree and an amazing array of stuffed birds, including the chance to compare the egg of a hummingbird, smaller than a little finger nail, with that of an elephant bird (now extinct), almost football-sized. Beyond is the Red Zone. Earths Treasury is a mine of information on a variety of precious metals, gems and crystals; From the Beginning is a brave attempt to give the expanse of geological time a human perspective. Outside, the delightful Wildlife Garden (Apr-Oct only) showcases a range of British lowland habitats, including a Bee Tree, a hollow tree trunk that opens to reveal a busy hive.

Many of the museums 22 million insect and plant specimens are housed in the new Darwin Centre, where they take up nearly 17 miles of shelving. With its eight-storey Cocoon, this is also home to the museums research scientists, who can be watched at work. But a great deal of this amazing institution is hidden to public view, given over to labs and specialised storage.

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