We decided to walk down from Machu Picchu to Aguas Calientes - after all, the trail was clearly lined with stones and had steps for the steep parts. No big deal, right? 

My shins and calves have never hurt so much before! It felt like I'd run a marathon! I'm in reasonable shape and no stranger to exercise, so I don't know if it had to do with the altitude, or what. Of course the porters returning from the Inca Trail were effortlessly running up and down, as were some local kids. Talk about feeling old & out of shape!