What is the most authentic place to ride?

There is around 100 metres (possibly 110 ?) of road leading down from Clerkenwell Road going East, just before it crosses Farringdon Road which is pretty authentic, there is a section near the start (around 15 meters in) which is a little less authentic, although it can't be any longer than 6 metres - so if you are going at pretty decent speed you don't really notice it.

Also there are some small patches of Oxford street that are pretty authentic to ride although they tend to be sporadic and short (2 or 3 meters) and are surrounded by large areas of unauthenticity.

This is also very authentic.

Blackstone Edge, on Rishworth Moor .