The Ara Pacis Augustae ('Altar of Augustan Peace') is an altar in Rome dedicated to Pax, the Roman goddess of Peace. The monument was commissioned by the Roman Senate on July 4, 13 BC to honor the return of Augustus to Rome after three years in Hispania and Gaul and consecrated on January 30, 9 BC. Originally located on the northern outskirts of Rome, a Roman mile from the boundary of the pomerium on the west side of the Via Flaminia, the Ara Pacis stood in the northeastern corner of the Campus Martius, the former flood plain of the Tiber River and gradually became buried under 4 metres of silt deposits. It was reassembled in its current location, now the Museum of the Ara Pacis, in 1938.
The altar reflects the Augustan vision of Roman civil religion. The lower register of its frieze depicts vegetal work meant to communicate the abundance and prosperity of the Roman Peace, while the monument as a whole serves a civic ritual function whilst simultaneously operating as propaganda for Augustus and his regime, easing notions of autocracy and dynastic succession that might otherwise be unpalatable to traditional Roman culture.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.