Here are 31 of the most enduring and perplexing unsolved mysteries, from grisly murders and ghost ships to great escapes and entire colonies of people disappearing without a trace.
The Alinosi Ice Cream Shoppe in Detroit was once the cat's meow. Now it appears 8 of its 9 lives have been lived. There is hope for the boarded-up, nearly abandoned building as it's for sale.