For more than six centuries, Russian artists basically painted one thing: icons, in nearly infinite variation, often with inspiring (or haunting) skill. So when you come to Moscow, where I am now, and step into the various cathedrals within the Kremlin walls, what do you see? Icons.
Then you move on to the old and new Tretyakov Gallery, which is really a museum and to Russian masterworks from the last 10 centuries or so. And there, besides a bunch more icons, you get to see what happened when the Russians decided to start painting portraits and landscapes. Great things, in a big hurry.
If that seems like an awfully reverent, artsy day of tourism, keep in mind that A) it keeps a body out of the freezing breeze; and B) the newer Tretyakov Gallery goes off in all sorts of wacky contemporary directions, including pop culture and politics.
In fact, if you step outside into the sculpture area, you find Moscow's version of the Island of Lost Toys: a whole garden filled with Lenins and Brezhnevs and many others whose likenesses aren't so welcome anywhere else.