This piece of music, Recondita Armonia , is from the opera Tosca...(not from the opera's final act). Puccini wrote some beautiful words to this music:

Pass me the colors...

Concealed harmony of contrasting beauties!
Floria, my ardent lover, is dark haired.
And you, unknown beauty, crowned with blond hair,
You have blue eyes,
Tosca has black eyes!

Art, in its mysterious way,
blends the contrasting beauties together...
But while I'm painting her,
My only thought,
My only thought is of you,
Tosca, it is of you!

I thought is was fitting for Otalia's final act!

Video created for entertainment purposes only.

Thank you to Venice The Series for last photo. http://www.venicetheseries.com/ (less info)