Nestled high in the misty central highlands of Chiapas, San Cristobal de las Casas is a feast for the eyes. The red-tiled buildings of its historic center are laid out in a classic colonial grid, radiating out from the town’s central plaza, the Zocalo. Tourists rove the adjacent streets, making their way past street sellers and buskers. There’s a chill in the air. In contrast to many of the more-touristed parts of Mexico, Sancris, as the locals call it, can get downright cold, a nasty surprise for tourists expecting Coronas and palm trees.