If you're planning a bit of sightseeing during your trip, head to Papal Palace of Castel Gandolfo— just one of the monuments in central Castel Gandolfo. Why not live the cultural experience and visit the cathedral, churches, and art galleries in the area— your sightseeing tour starts here. Castel Gandolfo has lots of other important landmarks you might want to see such as Colosseum, Trevi Fountain, and Pantheon.