On Dec. 16, MGM Mirage’s $8.5-billion, 18-million-sq-ft. CityCenter project debuted on the Las Vegas Strip. Perini Building Co., a unit of Sylmar, Calif.-based Tutor Perini Corp., was the general contractor, with Gensler, San Francisco, as executive architect. The seven-building, mixed-use development on 67 acres at one time employed one-third of southern Nevada’s building trades. The hotel, home and entertainment complex could resurrect or sink Las Vegas’ flagging tourism industry, possibly giving new life to stalled projects, say some observers. If unsuccessful, it could plunge MGM Mirage into financial trouble and slow southern Nevada’s economic recovery.