This is the Nikolskaya Tower (Russian: Никольская башня) which is situated on the eastern wall of the Moscow Kremlin. It was originally built in in 1491, rebuilt in 1806, and restored in 1816 after the top of the tower was blown up by the retreating French army in 1812. The towers were originally topped by gilded two-headed eagles that symbolized Tsarist Russia, however these were replaced by red stars representing the Soviet Union in 1935.
Russia, unfortunately, is not a country that you can jet off to for last minute holidays. Trips there require advance notice, as you must acquire a visa from your nearest Russian embassy or consulate. A trip to Russia is well worth the time and money, however, and remains one of my favorite places that I have visited in my eight years of international travels.