If you're a literature/Bulgakov buff, don't miss the Patriarshie Prudi park. That's where the Master & Margarita starts.

We had an amazing chance meeting there - asking some directions* from two beer drinking teen boys (one wearing an appropriate T-shirt!) we ended up discussing the book and Bulgakov in general with them. They even suggested to visit the nearby Bulgakov's flat and what to see there.

* we wanted to find this sign - they walked us there!