Take a day trip to the nearby city of Tarragona, a UNESCO World Heritage site known for its well-preserved Roman ruins. Explore the ancient Roman amphitheater, stroll through the charming old town, and visit the impressive Tarragona Cathedral. Don't forget to try some local delicacies at the traditional tapas bars and restaurants. In the evening, return to Salou and relax at one of the beachfront cafes.