Identify for me 5 key points of that tension in Paris. Where is it holding both the old and the new in tension?

-How do ruins fit into a city landscape? How does the past fit in with the present? Paris, the Capital of Modernity according to Balzac, exists at the intersection of decay and growth, of regret and hope. A city like Athens or Rome feels the pull of their history more strongly. A city like New York feels the pull of modernity. The history of Paris is one in which each new age uses the detritus of the previous age to build its own city. Build it back exactly the same and nothing changes. Reject it entirely and there is nothing to build with. Paris is a city that has managed to balance the old and the new, tradition and modernity, regret and hope. Our role this semester has been to adopt the role of intrepid explorers, excavating the buried secrets to learn from them by carefully brushing away the accrued material layer by layer.

Assignment:
Identify for me 5 key points of that tension in Paris. Where is it holding both the old and the new in tension? How is it doing so? Why might it want to hold onto that old piece of Paris? What does it represent? Why not get rid of it?