The rock reliefs at Naqsh-i-Rustam and Naqsh-i-Rajab, quite impressive and well-known works of art, date from the third century A.D. There are two groups of these reliefs in the Persepolis area. Nine reliefs are hewn into the rock below the royal tombs at Naqsh-i-Rustam; each relief is set in a rectangular recess. There is another group of four reliefs at Naqsh-i-Rajab, about three kilometers north of Persepolis. These reliefs are carved into three sides of a grottolike bay at the foot of the Mountain of Mercy. The exact purpose of this recess is not known, but it seems to have been a place of religious significance even before the Sasanian kings came to power. Since interpretations of the rock reliefs, both at Naqsh-i-Rustam and Naqsh-i-Rajab, are still varied and disputed, and since only a few of these reliefs have inscriptions, their identification-that is, dating-has had to be based mainly on depictions of specific kings on coins of the Sasanian period. Thus it seems that the earliest of these reliefs is one at Naqsh-i-Rajab. It shows an investiture scene of Ardashir I, founder of the Sasanian Empire (226–40 A.D.) by the god Hormizd (Ahuramazda), who is represented here in human shape. God and king are both standing and are of equal height. Only the fact that the god holds the diadem and the king reaches for it shows the dependence of the mortal king on the favors of the highest god. What makes this relief historically so important is its inscription by the priest Kartir, who was not only the founder of the Sasanian state church but also played an important role in politics. This inscription, proclaiming his personal beliefs, shows Kartir with hand raised in a gesture of homage to the god and the king. Another relief at Naqsh-i-Rajab depicts the investiture of Shapur I (241–72 A.D.), son and successor of Ardashir I. In an adjoining relief Shapur I is shown on horseback, followed by nine court attendants on foot.

Of the nine reliefs carved into the rock below the royal tombs at Naqsh-i-Rustam, the most important depicts the victory of Shapur I over the Roman emperor Valerian, whom he defeated and captured at Edessa in 260 A.D. The relief shows the king seated on his horse and Valerian kneeling in front of him. To the right of this scene is another inscription by Kartir, attesting to the victory and triumph of the Persian king over the Roman army—an unparalleled event in the reign of Shapur I. The rest of the Naqsh-i-Rustam rock reliefs deal mainly with equestrian scenes, showing various kings, e. g., Bahram II and Hormizd II.