[masklinn]

Note that you can also clean things up without tearing it down entirely. Many cities have retained historical centers in that style without keeping the "slum" bits, and it does makes for more interesting walking around than huge boulevards and avenues.

There's an architectural movement to come back to these more human-sized city designs too: smaller streets, more mixed use, less emphasis on large (and motorised) transportations, incorporation of structural shading and breeze-shaping, ...

[AdrianB1]

It works for small towns, not capital cities with multi-million inhabitants. Even with the (fabulous) dense underground network you need larger boulevards and parks, not 3 meter wide streets everywhere. I am not a fan of Champs Elysee (there are so many better places), but it gives some air to the city. I think Paris 200 years ago was claustrophobic and a maze.

[ldng]

See Strasbourg for an example of that. Center was left alone and 19th century building were built in a brand new neighboorhood.

[kmlx]

see brussels for a counter-example. tore down everything, and became of laughing stock for urbanists, and a sad place to live in for the rest of us.