How to draw perfect circles?

Video shows newly discovered Stonehenge-like site, revealed by extreme drought https://t.co/42IZorG1Mi

— pras (@bibli_pras) July 14, 2018

How do you make
a giant perfect circle

As kids we used bangles to
get a perfect circle

Bangles store perfect circles
in them

How is a bangle made


With a roller pin



Hows a rollerpin made

Back to the stonehenge
if it was small columns
you wait for the sun
shadows fill the circle
for you

start with a centre
put a stake in.
tie a rope to it
on the other end
have a stick

now mark the ground
pulling the tether
all around the stake.