Gustavo Dudamel takes the podium in front of more than 1,000 musicians for one last run-through of Mahler 8.

Three weeks of The Mahler Project here in Los Angeles, all leading up to this.

Tonight, of course, is the once-in-a-lifetime performance of Mahler 8, the "Symphony of a Thousand," at the Shrine Auditorium.

Over 1,000 musicians. Two orchestras. One conductor. And more than 6,000 concert-goers in attendance to see the music of Mahler at its most grand.

These photos are from today's dress rehearsal - just imagine what it will look like tonight.