Castel Sant'Angelo, originally built as a mausoleum for Emperor Hadrian, is now one of Rome's most important sights. The 2nd century building not only offers an insight into Roman history, but also into the architecture of the time. The palace has served various purposes over the years, including as a defensive fortress and papal residence. The exhibition inside shows its changing use and houses impressive works of art and historical artifacts. From the upper walkway, you have a far-reaching view of the city and the Tiber, which makes for ideal photo opportunities. Castel Sant'Angelo is also closely linked to the Vatican; a secret passageway connects the two buildings. A visit to this historic site combines an interest in history with an exploration of one of Rome's most impressive buildings. Plan enough time to explore the surrounding area and enjoy the unique views.