The Roman bridge in Sommières is 190m long. It was built on the instructions of Emperor Tiberius at the start of the 1st century. It was restored in the 18th century. At the town end of the bridge is the gothic town gate known as the 'Tour de l'Horloge'. Only 7 of the 19 arches can be seen, the others lie beneath the town where they act as cellars.
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.