Sacsayhuaman was probably the biggest surprise for me, and therefore the most exciting of all the ruins we visited. It is located about a 25 minute walk just up the hill from Cusco and has the most enormous boulders you have ever seen in your life, and they fit perfectly together over and over and over again. There is nothing like this at Machu Picchu at least not to this scale. And to top it all off, people who study these things are pretty sure that the boulders were brought from about 5 kilometers away, which is also different from Machu Picchu where all the rocks they needed were basically right there. So we took some snacks and waited for everyone to leave and watched the sunset. It was pretty amazing.