The Hermitage in St. Petersburg, Russia is a fabulous building (actually a series of connected buildings, one of which is the “real” Hermitage). The museum contains, of course, great pieces of art. It is also a historical site having being built in 1764 by Catherine the Great as the Winter Palace (more about the Winter Palace: http://en.wikipedia.org/wiki/Hermitage_Museum). But it is definitely an architectural jewel.
In another post I shared pictures of the spectacular chandeliers. Here I would like to focus on theceilings. I do not think I have seen ceilings like these in other European palaces, though perhaps it is more that the style of these ceilings is more to my taste not because other palaces’ ceilings are not spectacular in their own right.