Because they used Sexagesimal, we now have 360 degrees in a circle and 365 days in a year
I am reading a Novel that is set in 64AD and is about the Romans. It's just fiction, but I am not sure whether this bit is based on fact.
The Babylonians realised that 365 days in the year still wasn't exact, so they saved up all the extra hours & minutes and every 1462 years, they had a "Phoenix Year". They were apparently all kinds of prophesies about what bad things were going to happen. The book is about Rome burning in the Phoenix year.
Tall columns if they are actually straight are likely to appear somewhat shrunken in the middle; therefore they are sometimes made slightly swollen in order to appear straight. This outward curvature of the profile is termed an entasis and in the Parthenon column, which is thirty-four feet in height, amounted to about three-fourths of an inch. In some early Grecian works, it is said that this correction was overdone but that its omission entirely is quite unsatisfactory. Some authorities appear to believe that an excellent compromise is found in the Parthenon columns.
Part 2: is what my example was about, I haven't found anything yet about the details of the construction, I am going on my memory of the documentary.
I guess the main thing was the Greeks were aware of perspective & optical illusion.
Citizen: So how accurate are these distances you measure, with all that electronics?
Scientist: Very accurate indeed.
Citizen: OK, can you give me some numbers, so I can see how accurate?
Scientist: Yeah, sure - the distances we measure to these stars are accurate to 1 light year - that's pretty good considering the farthest ones are over 13 billion light years away.
Just a bit of a joke to illustrate varying ideas on accuracy.
Some people think that 1 degree of arc is pretty precise.
Some are really blown away when they discover a survey grade GPS records Latitude & Longitude to 5 decimal places of a second of arc - which gives a position coordinates to about 3mm precision.