Zaraysk kremlin (1525-1530) was built for defense from Tartar raids. It is a regular (meaning built according to a project) rectangular fortress with 8 towers and 4 gates. Walls and gates are fully preserved (Zaraysk has the only fully preserved kremlin in Moscow Region, which does not include Moscow). The kremlin is almost empty. The most remarkable building inside is Nikol’sky Sobor (St. Nicholas Cathedral, 1681), built in old Russian tradition after an order by Tsar Fyodor Alekseevich to accomodate the wondermaking ikon of St. Nicholas (Nikola of Zaraysk). Services are not performed regularly, and the cathedral is usually closed. Neo-classical Predtechensky Sobor (Cathedral of St. John the Baptist, 1901), regular services.
Tours to Zaraisk Kremlin by airport-transfers.ru