[fransje26]

Although the claim is slightly exaggerated, it should be kept in mind that the average lifespan of a reinforced-concrete building or piece of infrastructure is between 50 and 100 years.

Which is why quite a few bridges in the US and in Europe are in critical state and collapse from time to time.

[bluGill]

Having seen the floor plans of buildings that are 50 years old, they are already very dated and don't fit with modern needs. My house is 50 years old and the kitchen is horrible for use - it was considered state of the art in 1970 (and it has a major remodel in 1990), but the space allowed for a kitchen still shows the "women should be out of sight in the kitchen" sexism of the time. Now that women are not considered lesser, but people still have to eat (and thus cook) a functional kitchen where you can bring guests (again women didn't count as guests in the same way even though you invited them!) has become very important to modern houses.

[Suppafly]

>Which is why quite a few bridges in the US and in Europe are in critical state and collapse from time to time.

Bridges aren't comparable to buildings.