"OSUSUME" means recommended. The National Art Center Tokyo in roppongi is one of the OSUSUME spots in Tokyo. I sometimes visit there for lunch (Brasserie Paul Bocuse Le Musée on the 3rd floor is excellent!) and then go downstairs for browsing the museum shop "SOUVENIR FROM TOKYO" (you would love this shop!!), and of course take pictures - it's a great place for it :) It's a museum but often I don't actually see the exhibition there, there is so much more to this place! You can just pick your favourite designer chair which are found throughout the place and sit down for a quiet time if you get tired walking around, my favourite is the Egg Chair found downstairs.
Great architecture, too.