Answer:
It all began when the Romans overthrew their Etruscan conquerors in 509 B.C.E. Centered north of Rome, the Etruscans had ruled over the Romans for hundreds of years. Once free, the Romans established a republic, a government in which citizens elected representatives to rule on their behalf.
Then the Great Roman Empire started its supports in its historic construction.
Source:
https://www.ushistory.org/civ/6a.asp
Johnson served from 1865 to 1869, he was the first American president to be impeached.
1 mm = 0.0001m
450 x 0.001 m = 0.45 meters
