One of the coolest things was reading about the Wari culture. They had no written language, so what we do know has only been found out through archaeology, speculation, and tradition. Something which I found fascinating was that a way of keeping history recorded was through tying knots in strings. Each knot meant something and a series of strings could tell a story. I can't recall what it was called, but the way these people were able to keep records without a written language was really impressive.
After checking out the Wari exhibit and the permanent collection (which is free to everyone, by the way), mom and I enjoyed some tea and cake. It was a delightful afternoon!