Short answers, pulled from the story.
Red Square takes its name from the Russian word krasnaya, which archaically meant beautiful rather than red. The name was first recorded in its current form in 1661-62. Tsar Alexei Mikhailovich officially extended the name to cover the entire square, which had previously been called Pozhar, meaning burnt-out place.
Red Square and the Kremlin were added to UNESCO's World Heritage List in 1990, among the first sites in the USSR to receive that designation.
The Lenin Mausoleum is a granite and labradorite structure on the western side of Red Square that holds the embalmed body of Vladimir Lenin in an armoured glass sarcophagus. The current building was constructed between 1929 and 1930 to designs by architect Alexey Shchusev. It was preceded by two temporary oak mausoleums, the first erected in January 1924 shortly after Lenin's death.
Saint Basil's Cathedral was closed by the Bolsheviks in 1918 and its head was executed. Plans to demolish the cathedral to enlarge Red Square were ultimately not carried out, partly due to the personal resistance of architect Pyotr Baranovsky. Since the early 1990s, services have been held there at irregular intervals, though it primarily functions as a museum.
On the 28th of May 1987, West German pilot Mathias Rust landed a Cessna F172P light aircraft beside Saint Basil's Cathedral on Red Square. The incident caused a major scandal in the Soviet Air Defense Forces.
The two most historically significant parades were the 1941 October Revolution Parade, held while Moscow was under siege and troops marched directly to the front, and the 1945 Victory Parade, at which the banners of defeated Nazi armies were thrown at the foot of Lenin's Mausoleum. On the 9th of May 2010, the armed forces of France, the United Kingdom, and the United States marched in the Moscow Victory Day Parade for the first time in history.