Answers of Ronaldo

Don't go. it's the most hostile known place I've ever been to in my entire life.
Try Marseille, Montpellier, or Monaco instead.

Visit the mountains and country side.
Visit Sinai, Brasov, rasnov and the castles.
Visit the nightclubs and nightlife in Bucharest.
Try the local food and wine and tripe soup in the local restaurants.

Las Ramblas
Gothic quarter
Gaudi architecture spotting. Sagres cathedral
Fresh fruit juice from market
Walk up hill and see city view
Visit Nou Camp stadium
Walk along beach.
Party in Marina and along beach bars.