The Temple of Jupiter Anxur crowns Monte Sant'Angelo above Terracina, and the views from its terrace are extraordinary: the Tyrrhenian Sea, the Pontine Plain, the islands of Ponza and Palmarola on a clear day, and the ancient Via Appia cutting straight across the marshes below. Getting up here is reason enough to visit Terracina.
The structure you see is largely the vaulted platform on which the temple stood — a series of arched substructures in travertine and opus incertum dating from the late second century BC. The temple itself is largely vanished, but the platform's scale communicates the ambition of the original. The site is freely accessible; bring water, as the road up is steep and the hilltop exposed. The walk from the old town takes about 30 minutes through a network of lanes climbing the hillside.