"Lulu" is hardly the only opera that could be considered overly long.

The only opera I'll wear that to is the soap going on in my own little courtyard.

Based on a true story, it was Verdi's only contemporary opera, one inspired by events and attitudes of his time.

This is the only complete opera that Toscanini ever conducts on television.

It is the only nineteenth-century opera to have a rose named after it.

Beethoven's only opera, it did not suffer from neglect on his part.

It is the only comic opera that Wagner wrote.

It won't keep you waiting, and it's the only opera I know that may be too short.

I think it's the only opera he's ever heard of.

By far Ponchielli's most successful work and his only opera still regularly performed.