There are many tourist routes in Barcelona, depending on your tastes. I recommend:
For me it is one of the most beautiful routes, architecturally and artistically speaking. It focuses on the emblematic area of Ciutat Vella, in the Gothic Quarter. Highly recommend attractions are on this route: Picasso Museum, the Gothic church of Santa Maria del Pi, and Cathedral of Santa Maria del Mar.
You can consider Runnerbean's Free Gothic Quarter Walking Tour
There are many archaeological remains of Roman times scattered throughout Barcelona, of incalculable value. The necropolis and the wall are very worth seeing.
Artist focused tours
Depending on the artist you like, there are routes of Picasso, Gaudí, Miró ... all are incredible, but the most advisable is undoubtedly that of Gaudí, as it will help to understand the artist and his real motivations.
Barcelona Modernisme Route guide book is handy. Pick your copy from Modernisme Museum.
Collserola Scenic Tour
In the mountains behind Barcelona, this is definitely a very different route to all the others as it is very laid back. You can enjoy the best panoramic views, surrounded by nature.
Ghost tour of Barcelona
This is your route if you like paranormal events, and curious legends and stories of the city of Barcelona; there are many. It is on foot and lasts approximately 2 hours, in the famous Born district.
Go for this tour if exorcisms, witchcraft, and ghostly apparitions excite you.
City Sightseeing bus tour
The Water District Tour
One of the most enchanting tours aboard Goleta Karya, a spectacular boat with wooden decoration. You can enjoy incredible views of Barcelona, including the beauty of the Mediterranean Sea. All accompanied by exquisite background music. The tour starts in front of the famous Maremagnum shopping center, very close to the Barcelona Aquarium. Reservation recommended.
Without a doubt, a very original activity if you want to enjoy together with family or friends. For tourists, it is a very beautiful memory to take home, as you will receive spectacular photographs in very important enclaves of the city of Barcelona. This Photowalk tour includes explanations and photos in HD.
Spanish Cooking & Paella Course
This is one of the most popular and original courses for the tourist who loves Spanish gastronomy. It starts at La Boquería market, where the course manager will select the ingredients to cook the paella. It is a small tour that includes some explanations about the Spanish gastronomy. Afterwards you will go to the cooking school, very close to the market (in the Born district). You can taste the famous sangria while you learn to cook paella!
Barcelona has beautiful beaches that deserve to be visited. Hire a bike and go on a tour visitng different coastal towns along the Barcelona coast. You can either do it yourself or sign up for one of the organized tours. The organized tour operators also offer of trying authentic and traditional Catalan lunch in a "chiringuito" (beach bar, very typical in Spain). Groups are limited and you can wear your swimsuit.
Sunset in a cruise.
Without a doubt, one of the most exquisite experiences from the wonderful Olympic Port. During the trip you can taste different wines and snacks, and even bathe in the Mediterranean Sea. You can also take a diving suit and visit the beautiful reefs! Amazing background music and free WI-FI.
FC Camp Nou.
If you like football, this is your tour. This incredible Football Club Barcelona stadium is a must see for the sports-loving tourist. It includes a museum with excellent exhibits, as important trophies. This is a self guided tour.
Barcelona: The rose of fire.
An interesting tour that tells more than 500 years of history related to resistance and anarchism. Barcelona was nicknamed "The rose of fire" in the late nineteenth century by anarchists. You can visit the most famous enclaves where the most revolutionary historical events happened.
Looking for the Freemasons
This incredible tour will take you through emblematic Barcelona buildings, showing you hidden symbols and historical facts surrounding them. A magical and peculiar journey that will undoubtedly delight all those fascinated by mystery.
Barcelona has been the protagonist in innumerable novels by well-known writers. That's why there are several tours that are worthwhile. The most outstanding books that have tours based on them are:
Zafon: Shadow of the Wind
Falcones: The Cathedral of the Sea.
Mendoza: City of Marvels.
Barcelona Balloon Tour
If you have a few hours to spare make sure to go on this Spectacular tour, something unknown for the tourist. It lasts approximately 6 hours and you can see all the Vallés Oriental (province of Barcelona). Without doubt a unique experience, where you can have the best panoramic views and take home some great photos. Includes a traditional Catalan breakfast and a flight certificate.