Cabbies in this Eur. city spend 2 years gaining "the knowledge", mental maps needed to get a license
[DOC] [TLE] BBC NEWS | Science/Nature | Taxi drivers' brains 'grow' on the job [PAR] Mar 14, 2000 ... Cab drivers' grey matter enlarges and adapts to help them store a detailed 
mental map of the city, according to research.