Opening Oct. 6, at the Paine Webber Art Gallery in midtown Manhattan is an exhibit on the history of New York City theatre, with 125 photos, artifacts, posters and costumes spanning 1750-1997. The exhibition will be on view at the Gallery through Dec. 5.

The chronological display follows NY theatre as it moved uptown from City Hall to Union Square, to Madison Square, to Herald Square to the current Times Square.

On view will be illustrations and plans of some of the first theatres built in the U.S.; news clippings of the 1849 Astor Place riots; posters from P.T. Barnum's American Museum. Special attention will be paid to ethnic theatres in New York and on the way movies transformed Broadway theatre.

"Direct From Broadway: 200 Years Of New York City Theatre" (dates of the items notwithstanding) has been assembled by theatre historians Craig Morrison and Oscar Andrew Hammerstein, and organized by the Broadway Theatre Institute.

Admission is free to the gallery (1285 Avenue of the Americas at 51st St.), which is open Monday-Friday, 8 AM-6 PM. For more information call (212) 713-2885. --By David Lefkowitz