Question: When was a ballet company founded who's most popular performance is a two-act ballet choreographed by Marius Petipa and Lev Ivanov?
Sentence (from "The Slave (Petipa/Pugni)"): The Slave Girl (a.k.a. L'Esclave) is a ballet "Divertissement" in 1 Act, choreographed by the Balletmaster Marius Petipa to the music of Cesare Pugni, first presented by the Imperial Ballet for the Imperial Court at the Hermitage Theatre, on April 27/May 9 (Julian/Gregorian calendar dates), 1868 in St. Petersburg, Russia.
Relevant evidence: No