You may not believe but there are 2 Kremlins: the one everybody knows and another one - Underground. A secret net of caches and underground labyrinths has connected Kremlin with different part of Moscow. It was possible to get from the Kremlin even to Vorobyovy Hills.
Of of Italians, who designed and built the Kremlin was Pietro Antonio Solari. Before coming to Moscow he has been working with the Leonardo da Vinci. Some historians guess that Leonardo could personally participate in the construction of the Kremlin. There is almost exact correspondences in his drawings with some elements of the Kremlin walls.
The Kremlin was originally red, but in the XVIII century it was whitewashed according to the fashion of that time. In 1941, the commandant of the Kremlin proposed to disguise the walls and the towers. Artificial streets were built here. The Kremlin walls were drawn with houses. The mausoleum turned into a country side house with a gable roof. The Kremlin became red again in 1947 by the order of Stalin. In principle, it was logical: red flag, red walls, Red Square.