The Mausoleum of Elena is a monument of Roman times, which is along the Via Casilina in Rome and is the third mile of the ancient Via Labicana; part of a complex of historic buildings from the late imperial times. Built between 326 and 330 in the time of Emperor Constantine I, it was supposed to be his own tomb, but it was eventually used for his mother Elena, who died in 328. This area was a cemetery of the Singulares Equites (cavalry corps of the Roman army). The monument has kept the grave of Elena until the eleventh century, when the coffin was carried into the church of the Lateran (now preserved in the Vatican Museums). The original height of the monument was 25 meters, but today it is only 18 meters; it is a building with a circular plan. There is a lower cylinder of octagonal shape with recesses; one of which was the entrance, and an upper cylinder, smaller, with eight arched windows and a dome that to lighten its weight, empty amphoraes were included in the construction(in Italian ‘Pignatte’) now visible due to the collapse of time and this is why it is called Tor Pignattara (meaning Tower of amphoraes) and the surrounding area is also known under this name.
You can get to the mausoleum by the street of San Marcellino (adjacent to the church of Saints Peter and Marcellinus in Duas Lauros).