Les Troyens is an opera composed by Louis Hector Berlioz.
Captain Jean-Luc Picard listened to the aria Vallon Sonore from the opera Les Troyens in his ready room aboard the USS Enterprise-E during the Battle of Sector 001 in 2373. (Star Trek: First Contact)
The precise version listened to by Picard is contained in the complete 1969 studio recording pf the opera by the Orchestra & Chorus of the Royal Opera House, Covent Garden (featuring tenor Ryland Davies), conducted by Sir Colin Davis and issued on compact disc ASIN: B0000040Y0, September 10, 2002 on Disc 4, Track 1: Les Troyens: Act V, No. 38 - "Vallon Sonore" at approximately 3:30 into the track