Arco di Costantino, Rome.
The Constantine Arch is a three-pronged triumphal arch in Rome. He was erected in honor of the Emperor Constantine in memory of his victory at the Milvian Bridge (in 312) over his opponent Maxentius. The constant arc was begun in 312 and consecrated on July 25th 315. On this day Constantine celebrated the beginning of his tenth year of government (decennalia).