The Mausoleum of Cecilia Metella has been known since the Renaissance as a symbol of the ancient Appian Way and drew the attention of archaeologists, architects, draughtsmen and vedutists. This monumental tomb, built at the 3rd mile of the Appian Way between 30 and 20 BC, is situated in a dominant position with respect to the road, at the point where a leucitic lava flow dating back some 260,000 years, ejected from the Albani Hills, came to a halt. The information we have about the woman to whom it is dedicated is limited, as we only know some of her family connections: her father was Quintus Caecilius Metellus, consul in 69 BC, while her husband, more likely, was Marcus Licinius Crassus, who had fought alongside Caesar in Gaul and son of the famous Crassus, a member of the first triumvirate together with Caesar and Pompey. The Mausoleum of Cecilia Metella can, therefore, be interpreted as a commemoration of both the woman and the glories, wealth and prestige of her family. The square base is made of concrete conglomerate originally lined with travertine blocks, while the cylinder above, still covered by travertine slabs, has a marble frieze with bucrani and garlands of flowers and fruit interrupted by a high relief with a trophy of arms and the figure of a barbarian prisoner. Originally, the cylinder was topped by an earthen mound covered with vegetation. The interior of the tomb consists of a slightly conical burial chamber about 6.50 metres in diameter, open at the top with an oculus and lined with a brick curtain. At present, the top of the mausoleum is crowned by a peperino block masonry elevation that retains a Ghibelline-style battlement, the result of building alterations made by the Caetani family to convert it into the main tower of their castle.