Architecturally, the Ascension Cathedral is quite different from most other famous ones in Moscow or Novodevichy, this one being pure white sans onion domes.

Although It is in the suburbs, it is easily accessible by metro (17 rubles) like 4 stops from the central ring. But as the structure was under repairs and closed for visit, the trip was at best an afternoon's walk through the park. If really pressed for time in Moscow, outside the Kemlin, I would go to Novodevichy instead.