This view was taken from the spire of the cathedral. The one tall structure in the photograph is the campanile, a civil, not religious structure. I believe that this is the tallest structure in Siena, and it truly towers over the Campo.
Siena is the leading of the Tuscan hill towns. It is still reasonably small - about 60,000 residents. Some of the others are very small - just a thousand or so. All of them have one dramatic characteristic - the city fabric is quite dense, and it ends abruptly at the edge of the city - there are no suburbs. Since these towns are all on hilltops, they all offer stunning views of the gorgeous countryside. At the same time, these towns are all of medieval origin, with narrow, curving streets and comparatively small blocks. This is a truly beautiful way in which to organize a city. Some regard the Italian hill town as the highest form of urbanism ever achieved. I happen to prefer Venice, but the hill towns are very close second.
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