If you have trouble finding your way around the tidy Cartesian grid that defines Tulsa's street network, imagine learning your way around an ancient, complex, and chaotic street network, and keeping that map entirely in your head.

From the Transport for London website:

All licensed taxi drivers in the Capital must have an in depth knowledge of the road network and places of interest in London - the 'Knowledge'. For would be All London drivers, this means that they need to have a detailed knowledge of London within a six mile radius of Charing Cross. Suburban drivers need to have a similarly detailed knowledge of their chosen sector.

From a PDF document about the Knowledge of London examination system:

In order to complete the Knowledge you will need to know any place where a taxi passenger might ask to be taken and how to get there. To do this you will need to know all the streets, roads, squares etc. as well as specific places, such as parks and open spaces, housing estates, government offices and departments, financial and commercial centres, diplomatic premises, town halls, registry offices, hospitals, places of worship, sports stadiums and leisure centres, stations, hotels, clubs, theatres, cinemas, museums, art galleries, schools, colleges and universities, societies, associations and institutions, police stations, civil, criminal and coroner’s courts, prisons, and places of interest to tourists. Such places are known as ‘points’.

How do you organize all this information in your brain? You learn 320 "runs", divided into 20 lists of 16 runs. A run connects two major points, and you learn the route from one end to the other, the reverse route (which may differ because of one-way streets and turn restrictions), all points of interest along the way, and all points of interest with a quarter-mile of each end point.

After an introductory talk, you have six months to learn the first 80 runs, then you go through a self-assessment, just to see if you've got the hang of it. You have another 18 months to learn the remaining 240 runs. Then there are four stages of oral examinations, each of which may involve multiple exams before advancing to the next stage. According to Transport for London:

On average it takes an All London applicant 34 months to learn the Knowledge and pass through the examination process, 26 months for a suburban applicant.

Small wonder that that London cabbie was able to keep his composure when he unexpectedly found himself being interviewed on TV about an Internet intellectual property case. (Hat tip on the cabbie story to The Dawn Patrol.)