What fascinates me about the "centro" is how the buildings form a gigantic maze-like structure. The height of the walls, in contrast to the narrow streets and short inhabitants, creates a dialectic of domination and safety. If street signs didn't exist (and often, in Siena, they don't), there would be no way to know where you were going until you actually got to an intersection or a dead end. It's wonderful. It's almost like a city created for wandering.