Maxentius was a roman emperor from 306 until he his army was defeated by Constantine at the battle of the Milvian Bridge on 28 October 312. As if his death in the Tiber wasn’t enough, Maxentius was dragged from the river and beheaded.
He was a builder. Just outside of the Catacombs of Sebastian on a little rise you can see the remains of the Circus Maxentius, which could accommodate some 10,000 people. Near the circus are also scant remains of the villa of Maxentius.
Unfortunately much of what we know of Maxentius comes from his rival Constantine. Thus the basilica built by Maxentius in the Forum is known as the Basilica of Constantine—or sometimes Basilica of Maxentius and Constantine.
In any case, on a stroll down the Appian Way from central Rome you’ll encounter the ruins of the circus right before you get to the Tomb of Caecilia Metella. They are aligned as in the picture below.
Here is a public domain image that shows how the circus would look in antiquity. The obelisk you see is now in the Piazza Navona. Note that this view is “backwards” from the picture in that it shows the rounded end of the circus in the foreground.
The location of the circus and villa is visible on this hand-drawn map found in the Capo di Bove farmhouse museum found a little further up the Appian Way.