Legend has it that Circe, a sorceress met by Ulysses during his Odyssey, used to live at Monte Circeo, and her profile can still be seen nowadays outlined by the mountain crest. And the hike to the summit of Monte Circeo really is enchanting: In addition to the spectacular veiws from the summit, you'll hike through thriving vegetation that characterizes the trip, including colorful flowers and trees with incredible trunks that acquire peculiar shapes. It is a truly unique opportunity to climb a mountain so close to the see, and you'll enjoy beautiful views and endless horizons along the way.
The route is characterized by steep uphills and downhills, which make it quite engaging. Expect to scramble in places and use four points of contact. Nevertheless, the route is very popular and can be very crowded, especially during weekends, even though many hikers stop at the false summit and turn back.
This is also a beautiful place to enjoy the sea. The very long shore right under Mount Circeo is very popular in Central Italy. Also, it's a climbing area with beautiful multi-pitch opportunities, though they can be quite hard to reach. Nearby, Sperlonga and Gaeta offer a wide variety of climbing options (these are all winter crags).
Note that this hike becomes rather exposed in places, so it is best to avoid on hot days.