While climbing the Great Wall, I felt the rumblings of a gastro-intestinal crisis. Fortuanately, on the way back down I spotted a sign in English with the international icons for toilets. To get to them you climbed down some stairs that were an original feature of The Wall down to the outhouse. At the bottom of steps a vendor was selling packs of toilet paper for 1 RMB (US$0.07). I doubled up and it was the best money I spent.