ancient works

Why is Roman concrete 2,000 years ago more sustainable than modern concrete?
the ancient roman ports of concrete built 2000 years ago still exist firmly until now. meanwhile, many modern works today have less than half durability and have a lifespan of less than 100 years.
Strange similarities of ancient works
in the world there exist ancient buildings of different civilizations on opposite sides of the hemisphere but have quite similar architecture to each other.