LOS ANGELES (June 25, 2012)—The Los Angeles County Museum of Art pulled the covers off artist Michael Heizer's latest creation over the weekend--a 340-ton boulder positioned to appear as though it's floating in midair.

About a thousand people showed up under a sunny sky as the gigantic work titled "Levitated Mass" was unveiled Sunday on LACMA's rear lawn, where it is intended to remain forever.

Its centerpiece is the two-story-tall chunk of granite that was hauled 105 miles from a Riverside rock quarry earlier this year.

Since then, the rock has been carefully positioned above a 465-foot-long trench that museum visitors can stroll.

Heizer, 67, who rarely appears in public, was on hand for the ribbon-cutting ceremony and led the first procession under his work of art.