I'm not sure what you're saying, but I'm very likely to live in a city older than yours. Buildings hundreds of years old are castles, churches or a limited number of inner city monuments. They are very hard to live in, let alone live comfortably in; they are very expensive to retrofit and in general nice to look at but a pain to live or work in.

Buildings 200 to 100 years old are more common, but still suffer from many defects; unless renovated in a way that is essentially 'build a new house inside the old one'. Which is more expensive than knocking the old one down.

Anything less than 100 years but older than say 20 can be made to 'modern' standards, for some values of 'modern'. It won't be nearly as comfortable as a new house though, again unless renovated the expensive way.

Housing needs change. If you think we Europeans build for 100+ year use, you obviously know nothing about real estate or construction, and the history thereof. If you think the fact that we have a bunch of old buildings is because they were designed that way, you are very mistaken.

I'm trying to say that while uses change that building is "effort" and if you're going to do it you should do it with the assumption that it will last.

Re-purposing old buildings is very common in the UK, and whilst sometimes that might mean essentially ripping it all out and rebuilding form the inside-out that's an extreme case. When it comes to "public buildings" and "houses" that people live in mostly the changes aren't so drastic.

I'm sure that people putting up buildings in the 1600s didn't imagine they would still be in use, but the fact that they are is a good thing. What I'm really trying to say is that planning to build something with the assumption it'll be dead/useless/retired in a hundred years seems wasteful and short-sighted. Europe is used as an example of how things have turned out otherwise. Though I appreciate there aren't any skyscrapers/tower-blocks of that age in the world. Unless you think of tenement buildings from the 17/18/1900s.

What a bizarrely hostile-feeling response. I'm not sure the person you were responding to was making the point that we are building for 100+ years of use, simply that most properties where he lives were easily as old as that and experienced little in the way of issues.

None of the 100/200+ year old houses and flats I have lived in - both within the UK and other older European cities - have had any major defects beyond what some of my other acquaintances living in modern buildings have experienced. They have all been perfectly "comfortable" as a 'new build' property.