In Scarface, was the mansion owned by Tony Montana a real house, or was it just a set built for the movie? If it was real, where was it located?

It's apparently a real mansion. Though set in Miami, none of the scenes were actually shot in Miami in fear of Cuban protestors. It was mainly shot in Southern California.

via:

http://www.jgeoff.com/scarface/sf_notes.txt

"The second home -- seen as Tony's Coral Gables mansion -- has an even more exotic history. The work of Bertram Goodhue, it was conceived in 1906 as a steel and concrete version of a neo-classic Roman villa -- containing one vast bedroom (which various owners would later remodel to suit their whims and needs) -- on a 35-acre plot.

Its original owner was a gentleman named Gillespie, whose other properties ironically included the palace in Havana which Castro later assumed as his headquarters.



Among the features of the estate were an artesian water system which fed a network of lagoons and lakes, one of which boasted an Egyptian barge for private parties, and the world's largest collection of palm trees, many of which were transplanted in the early 1950s to become the "Jungle Ride" at Disneyland.

Previous residents included author Thomas Mann, who entertained such house-guests there as Albert Einstein and Winston Churchill. And when director De Palma staged the wedding of Tony and Elvira on the lavish grounds, he could refer to a previous, equally celebrated ceremony on the same site, in which Charlie Chaplin and Oona O'Neill were united.



The pleasure of these surroundings was somewhat diminished by another blow from the weather. The crucial wedding sequence was postponed when the California coast was hit by record-breaking storms which wreaked millions of dollars in damages in Santa Barbara County alone.

Daily reports were phoned back from Montecito to Los Angeles, assuring De Palma and Scarfiotti that the villa -- and the luxurious amenities the film crew had added -- were still intact.

Meanwhile, key interiors were talking shape on the sound stages at Universal, including the newlyweds' round cream and gold bedroom, complete with private sunken Jacuzzi, and Tony's "office," a pagan sanctum of black marble walls and gold fixtures."

http://www.answerbag.com/q_view/7519