The Fair Association had hoped for the arena to be open by the fall of 1921 to inaugurate the new fair, but it was not ready. The million ( in dollars) building had its official public opening on December 16, 1921, attended by 5,000 persons to see an athletic meet put on by the "Sportsmen Patriotic Association." Upon completion, the building was billed as the largest of its kind in North America. The name "Coliseum" was given to the building in 1922, in time for the opening of the CNE. The main entrance was to the north, along Manitoba Drive. The southern side of the building was along the main TTC streetcar rail lines serving the CNE, which separated the Coliseum and Industry Buildings to the north, and the later Engineering and Electrical Building (1928) to the south. In 1926, additions were built and the complex was claimed to be the largest structure of its kind under one roof in the world. In 1931, the Horse Palace was built next door to provide a permanent building for the stables of the Winter Fair.