What does a city’s rooftops reveal about it?

I was flying over Lyon last week—low pass, just above the roofline—and something struck me. Not the bridges or the river, but the way the rooftops leaned into each other, like old men huddled for warmth. Tile, metal, slate, some with solar panels crammed on top like afterthoughts. I started wondering: if you could only see a city from above, what would you know about its rhythm? Its memory? The way roofs slope toward the sun, or away from it. What do they say about who lived there, and who left?