Can you arrange these 25 Roman letters into a square that reads four ways?
An ancient graffito found at Pompeii uses exactly five Latin words, each five letters long: SATOR, AREPO, TENET, OPERA, ROTAS. Arranged correctly into a 5×5 grid, the square reads identically left-to-right, right-to-left, top-to-bottom and bottom-to-top. Can you work out the arrangement before checking the answer?
Reveal the answer
The words stack in that exact order, SATOR / AREPO / TENET / OPERA / ROTAS, one below the other, so the letters in each column spell the same five words reading down as the rows do reading across, and the whole grid reverses perfectly too since TENET is a palindrome and ROTAS mirrors SATOR. Copies have turned up from Britain to Syria; nobody agrees on what it means, or why it spread so far.
— Unknown (earliest known example found at Pompeii), Sator Square — before 79 AD