O'Neill's Bridge on the Moon - Introduction and Flyover
On July 30, 1953, as the Sun was setting over the western shore of Mare Crisium, science writer John J. O'Neill observed a patch of light on the mare floor that appeared to emanate from the low spot between Promontorium Olivium and Promontorium Lavinium and spread to the east. Incorrectly interpreting the pattern he saw as light passing under the arch of a 12-mile wide natural bridge O'Neill sent letters seeking confirmation of his discovery to a number of prominent lunar observers of the day. Source