This nails it. Most first world countries managed to build most of their concrete infrastructure in the 60s and 70s. Unfortunately, little since then and maintainance isn't so easy.

It's impressive what China builds - they were decades behind but times changed. A huge parts of Shanghai city were rice field until 1990. Most skyscrappers were build since 2005. And now Shanghai has probably more skyscrappers than any other city in the world. Impressive also the amount of 2 or 3 story highways and the high speed trains.