Planning a trip to Barcelona and wondering what to see and do? Here’s my 3 days in Barcelona itinerary for visiting the vibrant Catalonian capital. In three days, this Barcelona itinerary takes you to all of Barcelona’s top must visit attractions, world class museums, and vaunted landmarks. You'll find all the best things to do in Barcelona in 3 days -- Sagrada Familia, Gaudi architecture, amazing museums, and charming neighborhoods. Read on for how to spend three days in Barcelona!