In the next month or so, Los Angeles will lose perhaps it greatest (sanctioned) ode to public art: LACMA’s parking garage, which is to be torn down to make room for the Eli Broad collection’s new home. If you’ve never paid close attention — or the money to park inside — now’s the time to check out the celebration of street art it has become since October 2000, when husband and wife team Barry McGee and Margaret Kilgallen were commissioned to “bomb” the second floor of the structure in commemoration of the show “Made in California.” Over the last five years, Kilgallen’s smoking, trudging, scowling women and McGee’s signature sad-sack faces and meticulously drawn messages have inspired uncoerced homages from several locally and internationally known artists: N.Y.-based graffiti trio FAILE’s collage stencils; Spanish tagger PEZ’s bubbly alien figures, and Obey Giant guru Shepard Fairey’s looming wheat-paste policeman. Others have left their marks, and their marks have left the building, thanks apparently to a new kind of art thief: a panel by Meta disappeared, and rumor has it that a mosaic by the French phenom Space Invader was chipped away. And now the real chipping begins. Although LACMA officials say that all of the garage art has been photographed for the archives, no plans have been made to preserve any part of the actual structure. On November 27, to “acknowledge change at the museum,” the top level of the parking structure will be opened to the public for a “chalk-in” celebration, from 11 a.m. to 5 p.m. People will be encouraged to contribute chalk drawings inspired by wall-projections of pieces from the museum’s collection. A DJ will add mood music. It’s free. Most graffiti fans and the artists themselves will likely argue that the beauty of street art is in its impermanence; that the destruction of the art left to LACMA’s garage is a fitting end. But one can only hope that the energy and spirit used to create that art can live on in the new Eli Broad building — or on it.