The Roman bridge of Salamanca crosses the Tormes River. Actually it is a construction of two separated bridges by a central fortification: the old bridge which extends along the portion near the city and it is of Roman origin, and the new bridge. Of the twenty-six arches, only the first fifteen date from Roman times. The bridge has been restored on numerous occasions and has survived several attempts demolition. Many of the restorations have been poorly documented, leaving for the study of archaeologists a great part of the work of determination, dating and explanation of the construction techniques of the ancient. The date of the construction of the bridge not is precisely known, but is among the mandates of the Emperors Augustus (27 BC-14 AD) and Vespasian (69-79), making it a bimillennium architectural monument.
The bridge is presented in the 21st century as a result of several restorations. One of the disasters that most affected it was the Flood of San Policarpo (January 26's night) of year 1626. From the construction of a third bridge for road traffic it remains a unique way of pedestrian and walking uses.
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.