c. 100 BCE
Technology
Roman Republic
Roman concrete
Volcanic ash mixed with lime yields a cement that sets underwater.
Why it mattered
Domes, harbours and aqueducts that still stand two thousand years on.
Antiquity
100 BCE
2 recorded milestones at this point in the record.
c. 100 BCE
Science
Greece
Hipparchus and the star catalogue
Hipparchus measured stellar positions, discovered precession and built trigonometry for astronomy.
Why it mattered
Made the sky quantitatively predictable.
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