Licensed taxi drivers in London need to have a detailed knowledge of roads and places of interest in London – this intimate acquaintance with the myriad of streets in a six-mile radius of Charing Cross known is known as “The Knowledge”. It takes between two to four years to learn and pass the test. Once you are licensed you can work anywhere in the Greater London area.
On scanning the brains of 16 London taxi drivers, who had spent an average of two years learning the Knowledge, University College London found, cabbies had a larger right hippocampus than control subjects.

The scientists also found part of the hippocampus grew larger as the taxi drivers spent more time in the job.

Great little video on our “Brainy Cabbies”. There a few seconds of ads before the video starts but well worth the watch.