Construction crews are building the fake post office in Harmony to be used in the filming of the movie “American Pastoral” later this month. The “post office” on Mercer Street across from the Harmony Museum will be blown up in one of the film’s more graphic scenes in a controlled explosion. Filming will occur Sept. 28 and Oct. 1. Scottish award-winning actor Ewan McGregor, who has been in “Trainspotting,” “Star Wars,” “Moulin Rouge!”, is starring and directing the film in his directorial debut. The film, based off Philip Roth’s Pulitzer Prize-winning novel of the same name, also will star Jennifer Connelly and Dakota Fanning.