The years in between
After Sir Henry Pellatt left Casa Loma, it sat vacant while proposals were considered for its future use. In 1925, one year after Sir Henry retired to his farm in King, the architect William Sparling put forward a proposal to convert the house to a luxury hotel.

William Sparling was granted a long-term lease, and began the process of completing the Great Hall and the Billiard Room, areas that Sir Henry had never himself finished. He also had plans to add two large wings to the east and west sections of the main building that would each contain 96 full suites and 56 rooms. These wings, costing approximately $1 million, were never built. A New York syndicate offered to purchase the Castle in 1928, but the deal was never completed and the hotel failed in 1929.

During the late 1920's, Casa Loma was also a popular nightspot. The Orange Blossoms, later known as Glen Gray and the Casa Loma Orchestra, were booked to play for eight months at Casa Loma in 1927 - 28. Shortly thereafter, they went on tour of North America with their big band sound.

With the onset of the Depression, Casa Loma sat vacant until 1933, when the City took the property for $ 27,303.45 in back taxes. Suggestions for possible uses of the building included a high school, a museum, an art gallery, a war veteran's convalescence home and later, a permanent residence for the Dionne quintuplets. None of the projects proved feasible and the City considered demolishing the castle. In 1936, The Kiwanis Club of West Toronto proposed that they operate the Castle as a tourist attraction. The City of Toronto agreed and in 1937 Casa Loma opened to the public after extensive refurbishment by The Kiwanis Club.

In August 2011, the new Casa Loma Corporation was formed. The City of Toronto remains the sole owner of the site.