Memorizing London's 25,000 streets changes cabbies' brains - and may prevent Alzheimer's

"To prevent further navigational anarchy, authorities created an exam to ensure cabbies actually knew where they were going. The test that ensued was a beast of a challenge. "The Knowledge of London" is widely regarded as one of the toughest vocational tests in the world. It requires drivers to memorize the labyrinthine web of streets within a six-mile radius of Charing Cross, the traditional midpoint for measuring distances in London."

"This is an area of about 113 square miles (293 km 2) of urban spaghetti. For comparison, that's about five times the size of Manhattan - but instead of straight streets and avenues, you have crooked lanes and ways. The area encompasses about 25,000 streets, which candidates must learn by heart. But that's just the skeleton. The meaty bit is the 100,000 landmarks they are expected to know and locate: hotels, hospitals, theaters, police stations, courts, clubs, p"

Becoming a London taxi driver requires memorizing The Knowledge, an exhaustive map of streets and landmarks within a six-mile radius of Charing Cross. The Knowledge demands learning about 25,000 streets and approximately 100,000 landmarks across about 113 square miles, an area far more complex than Manhattan's grid. The exam originated in 1851 after the Great Exhibition caused chaotic passenger demand and navigational failures, prompting authorities to require proof of navigational competence. Intensive study of this dense urban layout drives neuroplastic changes, physically restructuring and growing the brains of successful candidates and producing both negative and positive side effects.

Read at Big Think