The iconic square, with all the greatest sights and attractions, is the first place in Moscow you should visit.
The name originates in the colour of the bricks, and it's also a "pun" - krasnaya means both "red" and "beautiful" in the Russian language.
The square is, naturally, filled with people, but don't let that discourage you. You can easily spend half a day here, just by visiting all the attractions including the most famous ones - colourful Saint Basil's Cathedral, GUM department store or State Historical Museum.
The square is just as beautiful during the night.
Wikipedia https://en.wikipedia.org/wiki/Red_Square
Address Krasnaya ploshchad, 109012 Moscow, Russia
Coordinates 55°45'13.565" N 37°37'14.82" E