To judge from all the Astrakhan, bohemian embroidery, and furry Cossack hats crowding the stores this fall, there’s a distinctly Siberian nip in the air. The post–Cold War cultural lovefest will get another boost with the Guggenheim’s blockbuster “russia!” It’s an immense survey of art in the world’s largest country, from medieval icons to the post-Soviet irony of Komar and Melamid, and there’s good reason for that exclamation point. Many of the 250 works (like Kasimir Malevich’s iconic Black Square, on loan from the Hermitage) rarely travel, and a good number hail from the imperial collections of Peter the Great and Catherine the Great as well as the private collection of twentieth-century patron Sergei Shchukin. Look for Monet, Picasso, and other Western masters sprinkled throughout, in the spirit of glasnost, not least because the opening is timed to coincide with the 60th session of the United Nations General Assembly. If such sprawl leaves you overwhelmed, a more focused array of Slavic treasures can be found at the Met’s “Prague: The Crown of Bohemia, 1347–1437,” which demonstrates that long before bookish postcollegiate Americans discovered the Czech capital, King Charles IV and his sons went to great lengths to make it a cultural rival to Paris and Rome.