Ivangorod Fortress is a Russian medieval castle established by Moscovian Grand Prince Ivan III in 1492 and since then grown into the town of Ivangorod. The castle is strictly quadrilateral with walls 14 meters tall. The original castle was constructed in one summer. Its purpose was to fend off the Livonian Knights. The castle is strictly quadrilateral with walls 14 meters tall.
Ivangorod was won back later in the year by Muscovite forces from the Livonians, under the command of Prince Ivan Gundar and Mikhail Klyapin. Three thousand troops arrived to retake the castle, rebuild it, and construct a new barracks and stronger bastions. For almost 10 years, the land around the castle was in constant warfare. The fortress and the land around changed hands repeatedly. The castle was reconstructed and fortified many times, becoming one of the strongest defensive structures in the 16th century. The castle was in development until the 17th century, becoming a large, sprawling fortress with several lines of defense.
The Treaty of Teusina (1595) returned the fortress to the Russians. In 1612, the Swedes conquered the fortress, which was bravely defended by a voivode, Fyodor Aminev (b 1560s, d 1628) and his sons. By the Treaty of Stolbova, Ingria was ceded to Gustav II Adolf, king of Sweden. In 1704, Peter the Great captured the castle from Swedish troops, bringing the fortress back into Russian control. Inside the fortress, there are two churches: one is dedicated to the Virgin's Assumption (1496) and the other to St. Nicholas (built in the late 16th century but later reconstructed).
After the early 18th century, the military role of the fortress dwindled due to technological advances. In 1728, a review was carried out of the fortresses in this area, which concluded that the installation had been neglected, and had a low fighting efficiency. An order was issued for restoration of Ivangorod fortress, but after the inspection of 1738 the fortress was designated not adequate for defence purpose.
In 1840, some improvements were carried out in the fortress (roofs were changed), further improvements took place in 1863 and 1911-1914. During World War I, the fortress was captured by Germans on 25 February 1918. From 1919 to 1940, the fortress belonged to Estonia. Despite changing hands several times in the first half of the 20th century, the fortress played no significant role in fighting.
During World War II, it was first controlled by the Soviet Union (1940–1941) and then by the Nazi Germany (1941–1944), which established two POW camps within the fortress and left many of its buildings damaged after their retreat. After the annexation of Estonia by the Soviet Union in 1940 Ivangorod fortress was part of the Russian Soviet Republic. The town and fortress remained with Russia after the collapse of the Soviet Union and the restoration of the independent Republic of Estonia in 1990. Currently, the fortress serves as a museum.References:
The city walls of Avila were built in the 11th century to protect the citizens from the Moors. They have been well maintained throughout the centuries and are now a major tourist attraction as well as a UNESCO World Heritage Site. Visitors can walk around about half of the length of the walls.
The layout of the city is an even quadrilateral with a perimeter of 2,516 m. Its walls, which consist in part of stones already used in earlier constructions, have an average thickness of 3 m. Access to the city is afforded by nine gates of different periods; twin 20 m high towers, linked by a semi-circular arch, flank the oldest ones, Puerta de San Vicente and Puerta del Alcázar.