Droves of treasure hunters raided the deserts and crags of the American West in the mid-19th century hoping to make a fortune in gold, silver and copper. Of the thousands of mining towns that sprang up, most have disappeared, but a scant few remain as spooky reminders of dreams that failed. Each year, visitors from around the world journey to these ghost towns - some resembling Hollywood movie sets, complete with tumbleweeds, howling breezes and swing saloon doors; others no more than ruins accessibly only by four-wheel drive - to experience first-hand history frozen in time.