A) Moscow is located on the banks of the Moscow river. Around Moscow there is not that much forests, usually it's fields. Also Moscow isn't a green city, but nowdays there trying to make more parks and gardens. I know central park named by Gor'ky, garden named by Bauman and also popular garden Ermitazh. Most famous square in Moscow (and also in all Russia) is Red Square. Moscow is famous because it's the capital of most biggest country in the world. Moscow has old historical, soviet architecture and also lot of modern, so in Moscow everyone can find what he likes.
b) St. Petersburg is located on the banks of Neva river. St Petersburg is also not that much green city, but there are lot of gardens and parks, I think more than in Moscow. Unfortunately I don't know names of gadens and parks there, because I haven't been to St Petersburg. Most famous square in St Petersburg is Palace Square. St Petersburg is historical Russian city it doesn't look like typical cities of Russia. There are a lot of palaces and people come to there to see it. Of course St Petersburg has beautiful old architecture which looks like architecture of typical European city.