The Bridge of Ajuda is a dilapidated bridge that crosses the Guadiana River between Spain and Portugal. The bridge was constructed between 1520 and 1521, during the reign of King D. Manuel I of Portugal. During 1597, many of the archways were damaged or destroyed during flooding.
Between 1640 and 1642, Matias de Albuquerque, Governor of the Alentejo, began the refortification of Olivença with the construction of a third or fourth lines of walls. During this period it is possible that the bridge was rebuilt, since it was in a state of ruin at the time of the Governor's visit to Elvas and Olivença. However, it was partially destroyed by Spanish forces in 1657. It was then rebuilt in the same century.
In 1705, redoubts were constructed to reinforce the bridge over the Guadiana, designed by Manuel da Maia. In 1709 the bridge was partially demolished by artillery during the War of the Spanish Succession.
Eight arches remain along the right margin and 5 along the left margin, consisting of inconsistent rounded arches supported by talhamares. The archivolts, with two rows of staves, are supported by quadrangular pillars reinforced by high talhamares. Along the main platform, an old tower was erected along the sixth arch of the right bank, which was constructed over large boulders, now visible along the margin.
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.