Metropolitan Opera History
A history of one of the world's leading opera companies.
http://www.metopera.org/history/

Evolution of Opera
Overview of the development of the operatic form.
http://members.tripod.com/~dorakmt/music/opera.html

Chinese Opera
A brief history.
http://www.hamilton.edu/academics/Asian/OpProg2.html

The Rise of Light Opera
A history of the development of the comic opera.
http://www.imagi-nation.com/moonstruck/spectop001.html

Timeline of American Opera
A chronology of important dates in the history of American opera.
http://www.hapka.com/usopera/timeline.html

Historic Opera
Archived images of historic opera singers, composers, and set designs.
http://www.historicopera.com/

Collecting Operas on Vintage Postcards
An illustrated introduction to collecting early 20th century European historical opera postcards.
http://www.luckymojo.com/operacards.html

A History of Opera in Fifteen Key Works
A concise description of the development of the art form using fifteen major operas as examples.
http://www.geocities.com/wanderingleopard/opera.html