Although the Haunted Mansion’s outer building was completed in 1963, the attraction didn’t open until August 1969. Walt had his workers focusing on projects for the 1964-65 World’s Fair. After the World’s Fair ended, the focus was put back on the Haunted Mansion. Sadly, Wald passed away and never got to see the completed attraction. Fifty years later, this remains one of the most popular attractions at Disneyland. The Haunted Mansion Holiday overlay is extremely popular during the holiday season.