The nations first twin theatre?
First of all, we are talking about movie theatres here. If we were including all theatres there would be many other twin or multiple auditorium theatres to include. It was the practice in the early part of the 20th century to build a 2nd smaller theatre above or on the roof of an existing theatre for use in the summertime. These were often partially open as to catch the evening breezes and create a more comfortable environment then was possible downstairs in the conventional theatre.
Other "stacked" twins were built so that one could be used as a combination house (both vaudeville and film), and the other strickly for vaudeville.
However, the first twinning that I know of, built with the intention to exhibit two different film programs occured at the Century Theatre in Baltimore.
The Century had opened in 1921, and was Baltimores leading presentation house. Above the Century Theatre was the Century Ballroom, a popular dancing and cabaret retreat.
It was purchased around 1926 by Loew's who decided to make better use of this prime piece of real estate by converting the ballroom into a 2nd theatre of the spanish atmospheric design seating 1,200 people.
The new theatre was called the Valencia. The two theatres shared a new large marquee and upright sign, vestibule and outer lobby. from there you took a short ramp up to the main lobby of the Century or got into elevators to go up to the valencia. They each ran first run movies, with separate admission (they both ran vaudeville acts as well).
Therefore here we have the oldest example (that I know of) of a theatre with two auditoriums sharing some facilities as a way to exhibit two films with separate admissions, in such a way as to spread the cost of such between the two.
Therefore the answers are: Century/Valencia theatres in Baltimore, Maryland by Loew's around 1926.
By the way, a popular joke in Baltimore back then was: What is the oldest theatre in Baltimore? Why the NEW Valencia of course...it's over a Century!
Mike: I don't know if there is a way to post pictures in this forum...so I'm sending you an e-mail with a picture of the first twin movie theatre. If you can post it...great!