The Simitai section of the Great Wall, at one point, has an incline of approximately 70 degrees. I planned on only a day of trekking out here but ended up spending the night in one of the distant towers far off the beaten track. Knowing I was only one of a handful of people who ventured this far out in decades, I left a note in a water bottle with my name, address and a brief message, curious as to when the next passerby should find it. To date, going on six years now, I have received no response.