When Meryl Streep and Robert De Niro finished "Falling in Love," they naturally went their separate ways -- Streep to London to film "Plenty," De Niro to visit Berlin.

But the rest of the movie's cast of thousands stayed on the set. Why? Because they live there. Director Ulu Grosbard shot the old- fashioned romance (in which Streep and De Niro, whose characters are married, but not to each other, meet, fall in love and -- gasp! -- don't make love) entirely on location in the streets and subways of Manhattan and Westchester County last spring, using the populace at large for local color.

Grosbard says there was a "movie glut" of sorts while he was shooting "Falling in Love" -- eight or nine other movie or television productions were being filmed, including Sidney Lumet's "Garbo Talks" and a Mickey Rooney television movie. So, even in a big place like Manhattan, it was inevitable that moviemakers would start bumping into one another. "It was funny," Belgian native Grosbard says. "At one point we were shooting in front of Saks, and then we planned to move down a few blocks to 56th or 57th Street. And we found the "Garbo" company there. They were there first. So we literally had to wait our turn. It lost us quite a bit of time."

Shooting on location is more exciting and more difficult, but the added texture and realism is worth it, says Grosbard, who chose public places such as Rizzoli's, Trump Tower and Grand Central Station as backdrops. But "youre constantly at the mercy of the unexpected. You go to a location for snow -- they've had snow for 20 years -- the year you go, no snow." And then there's the human element. "New Yorkers were amazingly easygoing," the director says. "They get blase about it. Even at Grand Central -- where we were the first company allowed to shoot in the daytime in 30 years -- you ask a crowd not to look at the camera, and usually they don't. But sometimes you lose a whole long take because some wise guy decides he's gonna wave to his mom."