Ithink the term 'grand correspondence' is perhaps less clear than saying an underground map is usually topological not geometric. If you look for 'geometric ma

Ithink the term 'grand correspondence' is perhaps less clear than saying an underground map is usually topological not geometric. If you look for 'geometric map tube' (or similar) you can see how the actual positions of the London stations differ from their positions on the standard (topological) map. There is another version of the standard tube map where the connections between stations are labelled with the walking distance between them.