The first "Disneyland" ever built was Disneyland Park in Anaheim, California. It officially opened its gates on July 17, 1955. It is historically significant because it was the only theme park designed and constructed under the direct and personal supervision of Walt Disney himself. Built on a former orange grove, the park originally featured five themed "lands": Main Street, U.S.A., Adventureland, Frontierland, Fantasyland, and Tomorrowland. While the opening day was famously chaotic—referred to internally as "Black Sunday" due to counterfeit tickets, melting asphalt, and ride breakdowns—it revolutionized the amusement industry by moving away from traditional "carnivals" toward a more immersive, cinematic, and family-friendly "theme park" experience.