From Smithsonian:
Most of us think of memory as a chamber of the mind, and assume that our capacity to remember is only as good as our brain. But according to some architectural theorists, our memories are products of our body’s experience of physical space. Or, to consolidate the theorem: Our memories are only as good as our buildings. In the BBC television series “Sherlock,” the famous detective’s capacious memory is portrayed through the concept of the “mind palace“—what is thought to be a sort of physical location in the brain where a person stores memories like objects in a room. Describing this in the book A Study in Scarlet, Holmes says, “I consider that a man’s brain originally is like a little empty attic, and you have to stock it with such furniture as you choose…”
The mind palace—also known as the memory palace or method of loci—is a mnemonic device thought to have originated in ancient Rome, wherein items that need to be memorized are pinned to some kind of visual cue and strung together into a situated narrative, a journey through a space. The science writer and author Joshua Foer covered this technique in depth in his book Moonwalking with Einstein, in which he trained for and ultimately won the U.S. Memory Championship. To memorize long lists of words, a deck of cards, a poem, or a set of faces, mental athletes, as they’re called, fuse a familiar place—say, the house they grew up in—with a self-created fictional environment populated by the objects in their list.
More here.