The one in which the city is named is of course The Barber of Seville.
The Barber of Seville and The Marriage of Figaro were both based on plays by Pierre Beaumarchais. They are in fact the first two plays in a trilogy, the third being The Guilty Mother. The Barber of Seville was first performed in 1775, and Rossini's opera of that title in 1816. The title of the second play in Beaumarchais' trilogy was actually The Mad Day, and The Marriage of Figaro was a subtitle. The play was written in 1778, but not performed until six years later; Mozart's opera was first performed two years after the play, in 1786.
The Marriage of Figaro is actually set in a palace outside Seville: the home of Count Almaviva, Governor of Andalusia, to whom the title character is valet and 'major–domo'.
Don Giovanni is based on the legend of Don Juan, which is set in Seville; but the city is not specifically named in the opera.
Carmen is explicitly set in Seville.
© Haydn Thompson 2018