Who has famously used memory palaces?

Roman orators (Cicero), medieval scholars, modern memory champions — and it's the "mind palace" of popular fiction.

• Cicero and Roman orators memorised hour-long speeches by walking a palace, one locus per argument — the technique is described in the Roman rhetoric manual Rhetorica ad Herennium.
• Memory-championship competitors use it to memorise decks of cards and thousands of digits.
• Fiction borrowed it as Sherlock Holmes's "mind palace" and in the book/film Moonwalking with Einstein, which follows a journalist who trains the method to championship level in a year.

The through-line: it's a trained method with a 2,000-year track record, not a party trick.