The biggest circle around I can offer (and a lot of triangles too), with a diameter of 33,7 m.
Itīs one of the two DEW (Dortmund Energy and Water) gasometers near the Dortmund port,
to supply the population of Dortmund with natural gas.
This is also part of my new gallery 'Dortmund Port':
For others taking part in the december challenge 'circles, etc...', look here: