Svyato-Troitsky Markov Monastery (Holy Trinity Markov Monastery) is one of two modern monasteries in Vitebsk (second one is female Svyato-Dukhov Monastery). Markov Monastery was founded in the 14th-15th century. A legend indicates that a certain Mark found a place to stay alone and built a chapel there. After he was joined by like-minded persons, who formed the monastery.
The monastery existed till 1576, after it was abolished and monastic Тrinity Church became a parish church. The monastery revived in 1633 by a duke Lev Oginski. In 1656 Patriarch of Moscow Nikon presented to the monastery a wonder-working copy of Kazan Virgin icon. In 1690 Pokrovskaya (Intercession) Church was burned down was reconstructed. In 1760 in this place the new preserved stone cathedral was constructed. Now it's covers to Kazan Virgin icon.
After October Revolution, in 1920 Svyato-Troitsky Markov Monastery was abolished afresh. All buildings except Kazan Cathedral of 1760 were demolished. Kazan church were the only Vitebsk church functioned in Soviet time. The monastery was revived 23 November 2000. Now it's situated at factory territory in the middle of factory buildings.
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.