"Ombra mai fu" (more popularly known as Handel's Largo) is the first aria in Handel's 1738 opera Xerxes ("Serse"). While the opera itself is not very well-known, this aria has become quite recognizable. If you are a fan of the movie Dangerous Liaisons or Pride and Prejudice, you will recognize this song as part of the movie soundtrack.
Vocally, it was originally written for a soprano castrato. In those days, women were not permitted to perform on the stage, so female roles were sung by men who were, ahem, enabled to sing in female ranges. But nowadays it is sung by tenors or mezzo-sopranos. Of course it is also readily performed strictly as an instrumental, so again it's a very adaptable piece for whatever wedding musician(s) you may be using.
Frondi tenere e belle
Tender and beautiful fronds