On Nov. 11, 1937, director Orson Welles, the archetype in boy geniuses, premiered a culturally historic, modern-dress version of Julius Caesar that put his freshly formed Mercury Theatre on the map. Richard Linklater's new movie, "Me and Orson Welles," chronicles the chaotic week leading up to this event. It was just hard — impossible — to find a stand-in for the venue itself; the Mercury Theatre on any map of today.

"We couldn't have shot it in New York," admitted director Linklater. "The Mercury was pretty ephemeral, anyway. I think it got torn down in the early '50s. It was right by Bryant Park, between Broadway and Sixth Avenue. That whole world is long gone."

In late November, to mark the spot — in conjunction with the film's release, of course — a plaque was unveiled at 110 West 41st Street (between Sixth Avenue and Broadway) proclaiming that this was the site of the original Mercury Theatre where Welles did his theatrical magic.

In attendance for this special event, in addition to director Linklater, were Zac Efron (in movie-star shades), the fictional "Me" of the title; Christian McKay, the factual and sometimes fatuous Welles of the movie, and one of Welles' daughters, Chris Feder.

So where did Linklater go to find his stunning approximation of the '30-vintage Mercury Theatre? Why, to the Isle of Man in the North Irish Sea, naturally. "Half the shoot — about three weeks — was done in this beautiful old theatre we found there in Douglas [the elegantly restored Gaiety Theatre, an almost exact replica of the old Mercury]."

The rest was lensed in London, and CGI effects of period skylines took it from there.

What was not a special effect was McKay's uncannily accurate approximation of the young Welles. That's called acting, and the heretofore-unknown Brit is eerily on target, vocally as well as visually. Occasionally, in closeup, he'll flash that celebrated smirk of a smile that Harry Lime used so memorably.

Harry Lime, by any other name, is "The Third Man," and a new 35mm print of Carol Reed's masterpiece will play Film Forum Dec. 18-29 in honor of its 60th anniversary.

— Harry Haun