The Palatine Gate (Porta Palatina) is a Roman Age city gate located in Turin, Italy. The gate provided access through the city walls of Julia Augusta Taurinorum (modern Turin) from the North side and, as a result, it constituted the Porta Principalis Dextra (Right-Side Main Gate) of the old town.
Built in the 1st century during the Augustan Age or the Flavian Age, the Porta Principalis Dextra may predate the construction of the city walls and was perhaps built on the location of an earlier Republican Age gate.
This facility served as a city gate for a long time and was turned into a castrum in the 11th century, although it lost the internal structure of the cavaedium over the centuries. In 1404, after centuries of incursions and partial decay, the western tower was rebuilt and both towers got completed with battlements for defensive purposes.
The Palatine Gate represents the primary archaeological evidence of the city's Roman phase, and is one of the best preserved 1st-century BC Roman gateways in the world. Together with the ancient theatre's remains, located a short distance away, it is part of the so-called Archaeological Park, opened in 2006.
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.