Laugh Factory / Show World Center / Times Square Arts Center
303 West 42nd Street / 669 Eight Avenue / 671 Eighth Avenue
I'm not sure exactly how everything on this block fits together or of the history. Show World Center has been there since 1977 and is one of the last survivors of Times Square's descent into hell in the 1970s. The live girls are gone although, supposedly, there are still physical remnants of its peep show days in the building.
The Times Square Arts Center is a more mysterious place. Although it has no website, it is listed as the home of a number of ethnic arts organizations. I believe it was once Nada Show World, the expensive collection of four theatres that in the 1990s lured Off-Off-Broadway impressario Aaron Beall away from his nurturing lower East Side roots and into financial ruin.
The Laugh Factory is the newest of the block's residents and apparently has an L-shaped configuration that wraps around the Duane Reade drugstore on the corner with a main entrance on the 42nd street side of the block. I seem to recall that it also has a porn background but none of the theatre history websites list any film or legitimate theatre that may have been there back in the day.
Next: Signature Theatre