"Levitated Mass" by artist Michael Heizer is the latest project at LACMA. On December 8, 2011, this 340-ton boulder, wide and in height, was ready to leave its quarry in Riverside County, after months of postponements. It sits atop the 456-foot-long trench which allows people to walk under and around the massive rock. The move started on February 28, 2012 and completed on March 10, 2012. The art piece was opened on June 24, 2012 by Heizer, Los Angeles County Supervisor Zev Yaroslavsky, and Los Angeles City Mayor Antonio Villaraigosa.