This city needs the time you can spare to get to every inch of it because you'll want to see every inch! There is so much culture and history and the sights are just amazing! I cannot stress enough the richness of how beautiful it is and how incredibly friendly the locals are!
Insider Tip:Take a bus tour or walking tour and get the feel for the city first, its huge and theres so much to do! Go to the opera house 2 hours before a performance for standing room and tickets are only 3 euros!