Welcome to Derinkuyu, an underground city that once housed up to people. In the Cappadocia region, famous for its cave dwellings and underground villages, Derinkuyu stands out for sheer size and complexity. Locals began digging in the BCE.
Floyd Patterson throws a punch at Muhammad Ali during their 1965 fight at Las Vegas Convention Center. Ali would go onto win by a TKO in the round. (Neil Leifer/SI) GALLERY: Never-Seen Photos of Muhammad Ali