Bellérophon

Lully's opera Bellérophon was revived this year in the occasion of the Festival de Beaune. It had been created in 1679 in Paris (Palais Royal) and hadn't been performed since the XVIIIth century.
Some audio samples of the opera (the prologue and the beginning of the second act) are on display here (at the end of the article).

Althought it was not Lully's first opera, it was the first of Lully's opera scores to be printed.
A copy of the original edition by Christophe Ballard can be found at the UNT Digital library.
(The UNT Digital Library is a great ressource for anyone interested in the history of music).