I'm not on about the Greek who looked down a well and saw the sun or shadows here and there.

I want to know if anyone has ever actually measured the Earth's circumference by normal means, whether it be a plane or whatever, where the actual starting point is dead centre back to the exact place.

Also, how does anyone know which is dead centre on the Earth to which they can take this measurement if there has ever been one?

Radius can be measured by normal surveying methods.

1) Find a high point that overlooks the sea

2) Sight the horizon from that point

3) Measure the angle between the horizontal & the horizon

4) Do a little trigonometry

5) Multiply by 2Pi to get the (approx) circumference

http://en.wikipedia.org/wiki/Radius_of_earth Biruni did it in the 11th century & arrived at a figure within a percent or so of the current accepted figure for the location he did it.