Taq-e Bostan ("the arch of the garden"): site of several Sasanian rock reliefs, on the northeastern outskirts of modern Kermanshah.
The small cave at Taq-e Bostan shows two kings, one of whom (the left one) is identified by an inscription as Shapur III (r.383-388). He came to power after much struggle, and presents himself standing next to his grandfather Shapur II (r.309-379), the great conqueror who had defeated the Romans - a victory he had celebrated with a relief at Taq-e Bostan. This representation is pretty original. Usual, a king showed that he was the lawful ruler by presenting himself as receiving power from the gods.
The identification of Shapur II is unproblematic, but it is far from certain that the inscription correctly identifies the king to the left as Shapur III, because his crown seems to be that of Ardašir III (r.379-383). It is certainly possibe that the monument was later "usurped" by Shapur III (compare Narseh's relief at Naqš-i Rustam).