The city is full of history and roman and a little gothic architectural heritage. We had a guided visit/tour and saw the Amphitheater, Roman walls, the cathedral, city council building, the Castellers statue, and more.
The most interesting thing I learned on the tour was the history of the amphitheater. The amphitheater was built in the 2nd century AD. It was first used as a place for gladiator combats and even as a place to execute prisoners. In 259 the Christian bishop (Fructuous) and his two deacons, Augurius and Eulogius were burned alive in the arena. This event inspired the construction of a church dedicated to the first martyrs by the Visigoths. You can still see remains that resemble sort of a church or a building structure. The amphitheater is still a place of religious value to those who live in Tarragona. We also saw the Casteller Statue and went to the beach. I definitely recommend going on this day trip with the program, although only for a few hours, you still get to learn a lot about the history of Tarragona and see some really cool sites.