When Disneyland, the entertainment brand's very first theme park, opened in Anaheim, California, in July 1955, Walt Disney and his Imagineers created a place where beloved characters, imaginative worlds, and groundbreaking attractions came to life. But even longtime Disney fans may not know some of the fascinating details hiding in plain sight. From Walt’s private apartment and secret Mickeys to a mountain that changed roller-coaster history, these 10 surprises reveal the extraordinary thought behind the original park.