Sticking out like, well, an Egyptian pyramid, this distinctive landmark looms over a busy traffic junction near Piramide metro station. A 36m-high marble-and-brick tomb, it was built for Gaius Cestius, a 1st-century-BC magistrate, and some 200 years later was incorporated into the Aurelian walls near Porta San Paolo. The surrounding area is today known as Piramide.
Note that the hour-long guided tours are in Italian.