Construction of the theatre began in 1738 but work was delayed by a number of problems (war, embezzlement etc.). The first theatrical performance only took place 14 years later. However, it is the oldest theatre still in use in France today.
http://www.tourisme-metz.com/en/sites-and-monuments/opera-theatre-de-metz-metropole-1_s.html#.Wieaw7T1UWo