What is kolomna kremlin?

Kolomna Kremlin is a historic fortress located in the city of Kolomna in Moscow Oblast, Russia. It was built in the 16th century to protect the city from attacks by the Crimean Tatars and other enemy forces. The fortress consists of several towers and walls, a bell tower, and a cathedral. The walls are constructed of red bricks and are up to six meters thick at some points. The towers provided a vantage point from which soldiers could observe and defend against any approaching enemy forces. The Cathedral of the Assumption was built in the 1530s and is one of the oldest surviving Orthodox cathedrals in Russia. Today, the Kolomna Kremlin is a popular tourist attraction and is included in the List of Russian cultural heritage sites of federal significance.