The method of loci was invented more than 2000 years ago, and widely used by the Greeks and later the Romans to memorize and give speeches that could last for hours. The Romans mentally placed the key points of their speech in locations along a familiar route through their city or palace. To remember a key point, they represented it by a concrete item, and visualized that item somehow interacting with a particular location. While giving their speech, they just mentally walked along the same journey through their memory palace.
