The Angarium (Latin; from Greek Ἀγγαρήιον angareion) was the institution of the royal mounted couriers in ancient Persia.
The messengers, called angaros (ἄγγαρος), alternated in stations a day's ride apart along the Royal Road.
These neither snow nor rain nor heat nor darkness of night prevents from accomplishing each one the task proposed to him, with the very utmost speed.
The first then rides and delivers the message with which he is charged to the second, and the second to the third; and after that it goes through them handed from one to the other, as in the torch-race among the Hellenes, which they perform for Hephaestus.
[2]A sentence of this description of the angarium, translated as "Neither snow nor rain nor heat nor gloom of night stays these couriers from the swift completion of their appointed rounds," is famously inscribed on the James A. Farley Building in New York City.