What about concrete?
It is the most used and most versatile building material of our time.
The Romans were the first who used cement in combination with stones to create massive and long-lasting structures.
With the fall of the Roman Empire the recipe got lost and was later found in the 18th century by the British Engineer John Smeaton.
I think it is incredible, that a lot of the Roman structures are still standing today. They were ahead of their time with this technology.