The Saviour Monastery of St. Euthymius was founded in the 14th century, and grew in importance in the 16th and 17th centuries after donations by Vasili III, Ivan IV and the Pozharsky family, a noble dynasty of the region. Among the buildings erected during this period were the Assumption Church, the bell tower, the surrounding walls and towers, and the seven-domed Cathedral of the Transfiguration of the Saviour. The cathedral was built in the style of the Grand Duchy of Vladimir-Suzdal. Its interior contains restored frescoes by the school of Gury Nikitin of Kostroma, dating from 1689. The tomb of Dmitry Pozharsky lies by the cathedral wall.
The monastery also contains a prison, built in 1764, which originally housed religious dissidents. The prison continued in use during the Soviet period, and among its better known prisoners was field marshal Friedrich Paulus, who was incarcerated here for a time after his surrender at Stalingrad. The prison now houses a museum about the monastery's military history.
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.