Rare, deadly, and often missed, some skin cancers develop in areas that rarely see the sun. Scientists are still learning about them, but here's what we know.

Known as “the city of darkness,” Kowloon Walled City was a crowded, tangled metropolis of 60,000 people with little political or legal oversight.

Your mouth is a magician. Bite the inside of your cheek, and the wound may vanish without a trace in a couple of days.