The challenge that "developed" countries / cities have is that there's already a lot of existing (and aging) infrastructure around. Meanwhile in other countrie

The challenge that "developed" countries / cities have is that there's already a lot of existing (and aging) infrastructure around. Meanwhile in other countries they build new cities from scratch, including infrastructure based on current-day knowledge of how these things pan out long term. I think the US has the space and funds to do so. If they were to build a new city from scratch for the next 250 years, what would it look like?