LSST marked a major milestone on April 14, 2015, with the traditional First Stone (Primera Piedra) ceremony taking place in Cerro Pachón, Chile. While site leveling has already begun, laying of the first stone is a Chilean tradition marking the construction start for a new astronomical observatory. The LSST First Stone was unveiled by (L-R) US Ambassador to Chile Michael A. Hammer, Chilean President Michelle Bachelet, NSF Director France Cordova, and LSST Director Steven Kahn. View the LSST site for more details.