Another one of the "must see" things in Beijing is the Yonghe Temple or Lama temple. Once a former imperial palace now one of the largest and most important Tibetan Buddhist Monasteries in the world. Things sure change in a couple hundred years, no?
Getting to the temple is a blast, as when you get close you are bombarded with incense sellers. It's customary to burn a lot of incense at the Lama temple, I even read somewhere that it was required to bring incense in with you. I ended up buying some before going in and had fun burning incense before all the halls.
The Hall of Harmony and Peace is the main building of the temple. It houses three bronze statues of the Buddhas of the Three Ages, the statue of the Gautama Buddha (Buddha of the Present) is in the center, it is flanked by the statue of Kasyapa Matanga (Buddha of the Past, right) and the Maitreya Buddha(Buddha of the Future, left).
The Pavilion of Ten Thousand Happinesses contains an 26m tall statue of the Maitreya Buddha carved from a single piece of White Sandalwood. You weren't supposed to take photos of this which is why you can't see it :(