In the neighborhood of the fort of Rainau-Buch, the remains of several other Roman buildings are visible. For instance, there is the ruin of a monumental gate in the limes wall near the modern village of Rainau-Dalkingen, about a kilometer north of the fort. Originally, it was a wooden construction, but it was rebuilt several times.
In the final phase, at the beginning of the third century, it must have had a façade like the stage of a theater, with rather plumb columns. In the upper part of the gate, there must have been a bronze statue of an emperor, perhaps Caracalla, who defeated the Germanic tribe of the Alamans in 213, and may have started his campaign from Dalkingen. Twenty years later, the Alamans stroke back, and the gate was burned down.
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.