This museum has superb information in Spanish and English on the archaeological excavations of Machu Picchu and Inca building methods. Stop here before or after the ruins to get a sense of context (and to enjoy the air-conditioning and soothing music if you’re walking back from the ruins after hours in the sun).
There’s a small botanical garden with orchids outside, down a cool if nerve-testing set of Inca stairs. It’s by Puente Ruinas, at the base of the footpath to Machu Picchu.