'Bedlam!' The very name conjures up graphic images of naked patients chained among filthy straw, or parading untended wards deluded that they are Napoleon or Jesus Christ. We owe this image of madness to William Hogarth, who, in plate eight of his 1735 Rake's Progress series, depicts the anti-hero in Bedlam, the latest addition to a freak show providing entertainment for Londoners between trips to the Tower Zoo, puppet shows and public executions.

That this is still the most powerful image of Bedlam, over two centuries later, says much about our attitude to mental illness, although the Bedlam of the popular imagination is long gone. The hospital was relocated to the suburbs of Kent in 1930, and Sydney Smirke's impressive Victorian building in Southwark took on a new role as the Imperial War Museum.

Following the historical narrative structure of her acclaimed Necropolis, BEDLAM examines the capital's treatment of the insane over the centuries, from the founding of Bethlehem Hospital in 1247 through the heyday of the great Victorian asylums to the more enlightened attitudes that prevail today.