A multiplex is a movie theater complex with multiple screens within a single complex. They are usually housed in a specially designed building. Sometimes, an existing venue undergoes a renovation where the existing auditoriums are split into smaller ones, or more auditoriums are added in an extension or expansion of the building. The largest of these complexes can sit thousands of people and are sometimes referred to as a megaplex.
The difference between a multiplex and a megaplex is related to the number of screens, but the dividing line is not well-defined; some say that 14 screens and stadium seating make a megaplex; others that at least 20 screens are required. Megaplex theaters always have stadium seating, and may have other amenities often not found at smaller movie theaters. Multiplex theatres often feature regular seating.
In about 1915 two adjacent theatres in Moncton, New Brunswick, under the same ownership were converted to share a single entrance on Main Street. After patrons entered the door, there were separate ticket booths for each theatre, and different programs were shown. The arrangement was so unusual that it was featured by Robert Ripley in his Believe It or Not! comic strip.
In 1937 James Edwards twinned his Alhambra Theater in the Los Angeles area by converting an adjacent storefront into a second "annex" screen. While both screens would show the same feature movie, one would also offer a double bill. It did not convert to showing different movies on both screens until some time after Nat Taylor (see below). On February 25, 1940, the Patricia Theater made news by becoming what is believed to be the first two-screen theater showing different movies when operator H. Bert Ram added a screen to an adjoining building and shared a common box office. The main screen remained the Patricia Theatre and the Patricia Annex became known as the Little Patricia.
In December 1947 Nat Taylor, the operator of the Elgin Theatre in Ottawa, Canada, opened a smaller second theater ("Little Elgin") next door to his first theater. It was not until 1957, however, that Taylor decided to run different movies in each theater, when he became annoyed at having to replace films that were still making money with new releases. Taylor opened dual-screen theaters in 1962 in Place Ville Marie in Montreal, Quebec, and at Yorkdale Plaza in Toronto, Ontario, in 1964.
Also in late 1947, but in Havana, Cuba, the Duplex movie theater was built to share the vestibule and ancillary facilities with the previously existing Rex Cinema (open since 1938); they were both designed by the same architect, Luis Bonich. The programming was coordinated, so that one of them showed documentary and news reels. while the other was showing feature films. They were in use at least until the 1990s.