The Victorian lunatic asylum has a special place in history. Dreaded and reviled by many, these nineteenth-century buildings provide a unique window on how the Victorians housed and treated the mentally ill.

Despite initially good intentions, they became warehouses for society's outcasts at a time when cures were far fewer than hoped for. Isolated, hidden in the countryside and surrounded by high walls, they were eventually distributed throughout Britain, the Empire, the Continent and North America, with 120 or so in England and Wales alone.

Now the memory of them is fading,...