To earn the right to operate one of London’s iconic black cabs, aspiring drivers must pass one of the hardest tests in the world, known as “The Knowledge.” It requires knowing central London’s maze of 25,000 streets in intimate detail. In oral exams, the applicant must recite an efficient route between any two points the examiner chooses. These can be drawn from more than 125,000 points of interest, from obvious landmarks like Buckingham Palace to an obscure back-alley pub. Those who pass the test study for an average of four years.

Not surprisingly, a good map is an essential study aid, and the map above is an example of the type many students use. It’s made by Geographers'