The Appian Way offers an easy walk on flat, paved terrain. Taking it from Via di Tor Carbone toward Castelli Romani and continuing along the Appian Way, just under a kilometer beyond the large nymphaeum of the Villa dei Quintili, you'll come across the imposing structure of Casal Rotondo. Located about 50 meters from the intersection with Via di Casal Rotondo, this majestic circular tomb dates back to the late 1st century BC. Over the centuries, it has undergone numerous reuses: in the Middle Ages, a peperino stone watchtower was built over the mausoleum and later incorporated into a farmhouse, now a residence.
Next to the tomb, the 19th-century architect Luigi Canina built a high brick wall to display some marble fragments found nearby, which he believed were part of the monument's original decoration. Among these remains was an inscription bearing the name "Cotta," which led to the hypothesis of a connection with Marcus Valerius Messalinus Cotta, son of the famous Messalla Corvinus, consul in 31 BC. However, more recent studies have revealed that these fragments belonged to another tomb, leaving the identity of the Casal Rotondo's true owner still unclear. The marble fragments of various sizes are today the defining feature of the complex.