This is the Kazan Kremlin sent by Anna via postcrossing [RU-230956]. She used amazing stamps :)
The Kazan Kremlin is the chief historic citadel of Tatarstan, situated in the city of Kazan. It was built on behest of Ivan the Terrible on the ruins of the former castle of Kazan khans. It was declared a World Heritage Site in 2000. The Kazan Kremlin includes many old buildings, the oldest of which is the Annunciation Cathedral (1554-62), the only 16th-century Russian church to have six piers and five apses. Like many of Kazan's buildings of the period, it is constructed of local pale sandstone rather than of brick. The cathedral bell tower was erected in five tiers at the urging of Ivan the Terrible and was scored to resemble the Ivan the Great Belltower in Moscow, but was pulled down by the Soviets in 1930.
Also of interest are snow-white towers and walls, erected in the 16th and 17th centuries but later renovated; the Qol-Şärif mosque, recently rebuilt inside the citadel; and the Governor's House (1843-53), designed by Konstantin Thon, now the Palace of the President of Tatarstan. The Palace is believed to be located on the site of former Khan's palace. Tucked between Presidential Palace and Söyembikä Tower is the palace church built on the foundation of medieval mosque.