Porte d'Aix (also known as the Porte Royale) is a triumphal arch in Marseille, marking the old entry point to the city on the road from Aix-en-Provence. The classical design by Michel-Robert Penchaud was inspired by the triumphal arches of the Roman Empire. The Porte d’Aix was initially conceived in 1784 to honour Louis XVI and to commemorate the Peace of Paris (1783) that ended the American Revolutionary War. Following the restoration of the Bourbon monarchy in 1814-15, the project was resumed in 1823, now to commemorate French victories in the Spanish Expedition, notably at the Battle of Trocadero, August 31, 1823. It was eventually completed in 1839, with a more general theme of victory.
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.