Background: James Lawrence Levine (; born June 23, 1943) is an American conductor and pianist. He is primarily known for his tenure as Music Director of the Metropolitan Opera (the "Met"), a position he held for 40 years (1976-2016). He was formally terminated by the Met from all his positions and affiliations with the company on March 12, 2018 over sexual misconduct allegations which he denies.
Context: Levine made his Metropolitan Opera (the "Met") debut at age 28 on June 5, 1971, leading a June Festival performance of Tosca. Following further appearances with the company, he was named principal conductor of the Metropolitan Opera in February 1972. He became the Met's principal conductor in 1973, and its Music Director in 1975. In 1983, he served as conductor and musical director for the Franco Zeffirelli screen adaptation of La Traviata, which featured the Met orchestra and chorus members. He became the company's first artistic director in 1986, and relinquished the title in 2004. In 2005, Levine's combined salary from the Boston Symphony Orchestra and the Met made him the highest-paid conductor in the country, at $3.5 million.  During Levine's tenure, the Metropolitan Opera orchestra expanded its activities into the realms of recording, and separate concert series for the orchestra and chamber ensembles from The Met Orchestra at Carnegie Hall. Levine led the Metropolitan Opera on many domestic and international tours. For the 25th anniversary of his Met debut, Levine conducted the world premiere of John Harbison's The Great Gatsby, commissioned especially to mark the occasion. On his appointment as general manager of the Met, Peter Gelb emphasized that Levine was welcome to remain as long as he wanted to direct music there. Levine was paid $2.1 million by the Met in 2010.  Following a series of injuries that began with a fall (see below), Levine's subsequent health problems led to his withdrawal from many Metropolitan Opera conducting engagements. Following a May 2011 performance of Die Walkure, Levine formally withdrew from all conducting engagements at the Met. After two years of physical therapy, Levine returned to conducting with a May 2013 concert with the Metropolitan Opera Orchestra at Carnegie Hall. On September 25, 2013, Levine conducted his first Met performance since May 2011, in a revival production of Cosi fan tutte. Levine was scheduled to conduct three productions at the opera house and three concerts at Carnegie Hall in the 2013-14 season. On April 14, 2016, Met management announced that Levine would step down from his position as Music Director at the end of the 2015-16 season. Levine was paid $1.8 million by the Met for the 2015/16 season. He assumed the new title of Music Director Emeritus, which he held until December 2017, when in the wake of allegations that Levine had sexually abused four young men, the Met suspended its relationship with him and cancelled all his future scheduled performances with the company.
Question: What did he perform?

Answer:
conductor