Djuma Mosque is the oldest mosque in Derbent and one of the oldest in Russia. It was built over a 6th-century Christian basilica around 733-734 AD. It has a 15th-century madrassa.
There are three naves in the inside of the mosque. The width of central nave is 6.3 m, side naves are 4 m wide. The naves are separated by square columns 97 to 97 cm wide, that have profiled capitals. The columns are connected by lancet arches.
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.