http://agathe.gr/guide/boundary_stones_and_house_of_simon_the_cobbler.html
Boundary Stones and House of Simon the Cobbler Inscribed marble posts were used to mark the entrances to the Agora wherever a street led into the open square. Two have been found in situ, inscribed with ... Diogenes Laertius records that ... simple text "I am the boundary ... here in the 5th century