Greenbelt Theatre, which anchored GREENBELT CENTER. Although conceived and built as a moving picture venue, it was dedicated with an evening of live performances, on May 6, 1938.
Photo from Library of Congress / Marion Post Wolcott

The first movie shown at the new cinema was Shirley Temple's "Little Miss Broadway", which started its Greenbelt run in September 1938. At that time, an adult ticket went for 25 cents, with a children's admission costing 15.   
Graphic from Wikipedia / "MovieMadness"

In an advert from a July 1939 issue of the local Greenbelt newspaper, we see that the city's movie theater is now air-conditioned. 
Advert from The Greenbelt Cooperator / Library of Congress