Cities, which have ancient or classical buildings are more interesting to people, becouse they have history in his walls, some tradition and inspiretions for next generetions. Contemporary buildings is not that bad, but impressive old buildings are graceful and really can be presious for town who have iconic monuments.
For Italy is Colosseum, for France is Eiffel Tower. These monuments is truly magnificent and ornate for this countries. This towns is really big and new, innovative buildings is neutral for his look. Old buildings is ornate for big countries, new buildings is elegent and give to us different perspective for architecture. For smallest cities, under fifty thousends residents, old architecture is attract to many tourists. Build a stylish, contemporary buildings, like The Sliding House in UK is not good idea, becouse town's look, where old building is next to new, innovative building is grotesque. Many small cities in Italy or France is truly amazing, becouse they have traditional and classical buildings. Many tourists is in euphoria when they can be there. This is argument for build new construct in old towns always in traditional style. Ugly, innovative construct can not be good idea for town where is only old buildings, becouse they do not fit there.
To sum up, old buildings is ornate for towns like Roma or Paris, innovative buildings do not interfere with them. But contemporary constucts in small, traditional towns are ugly and put off tourists. Only build in old style is good for these small cities.