The Roman Odeon, the most significant ancient monument in Patras, is in the upper town and was built around 160 AD, in the reign of either Antoninus Pius or Marcus Aurelius. It was severely destroyed by successive invasions, wars, and earthquakes. It was almost buried under the remains of other buildings and ground. It was in 1889 when the Odeon was found by accident while some workers were digging up the ground for the construction of the port. It has been restored and partially reconstructed, and is used as an open-air theatre for performances and concerts in the summer.
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.