The Ka'ba-ye Zartosht (alt: Kaba-ye Zardusht, Kaba-ye Zardosht, Persian: کعبه زرتشت‎), meaning the "Cube of Zoroaster," is a 5th century B.C.E. Achaemenid-era tower-like construction at Naqsh-e Rustam, an archaeological site just northwest of Persepolis, Iran. This enigmatic structure is one of many surviving examples of the Achaemenid architectural design.
The name Ka'ba-ye Zartosht probably dates to the 14th century, when many pre-Islamic sites were identified with figures and events of the Qur'ān or the Shāhnāme. The structure is not actually a Zoroastrian shrine, nor are there reports of it ever having been a pilgrimage site.
The structure, which is a copy of a sister building at Pasargadae,[2] was built either by Darius I (r. 521–486 BCE) when he moved to Persepolis, by Artaxerxes II (r. 404–358 BCE) or Artaxerxes III (r. 358–338 BCE). The building at Pasargadae is a few decades older. The wall surrounding the tower dates to Sassanid times.

Physical attributes
The square tower is constructed of white limestone blocks, that - unlike those of the sister building - are held in place by iron cramps. Mortar was not used in its construction. Each side of the building is 7.25 m wide. The 12.5 m high structure has a slightly pyramidal roof and stands on a 1.5 m high three-stepped plinth. Each face of the building is decorated with slightly recessed false windows of black limestone.
The structure has one square inner chamber, 5.70 m high and 3.70 m wide, access to which is through a doorway with a decorated lintel in the upper half of the tower. The chamber once accessible by a flight of steps, only the lower half of which has survived. The 1.70 m wide and 1.90 m high door was of solid stone that was originally firmly closed but has since disappeared.

Purpose
From a reference to fire altars in a Sassanid-era inscription on the building it was inferred that the structure was once a fire altar, or perhaps as an eternal flame memorial to the emperors whose tombs are located a few meters away. This theory has however since been rejected since the lack of cross-ventilation would have soon choked the flame, and in any case, the author of the inscription is unlikely to have known the purpose of the building seven centuries after its construction.
A later opinion suggested that both it and its sister building were safety boxes for the "paraphernalia of rule".Today, scholars consider the structure to be an Achaemenid royal tomb, and it has been observed by F. Weissbach and A. Demandt that both the Ka'ba-ye Zartosht and its sister building at Pasargadae "more closely correspond to the description of Cyrus the Great's tomb by Arrian (6.29) and Strabo (15.3.7) than does the monument in Pasargadae which is commonly attributed to this king.

Inscriptions
The Sassanid-era wall surrounding the structure has four inscriptions dating to the 3rd century.
The trilingual inscription ('KZ') of Shapur I (241–272) is on the eastern (Middle Persian text), western (Parthian text) and southern (Greek text) walls. A Middle Persian inscription of the high priest Kartir — the 'KKZ' inscription — is below Shapur's on the eastern wall.

Inscription of Sharpur
The trilingual inscription of Sharpur I, known as SKZ or KZ or Res Gestae Divi Saporis contains his account of the operation of his reign. It sheds light on the operation of the early Persian kingdom. It also contains a description of Shapur's Roman Wars which differs significantly from the account in Roman sources. Shapur claims to have defeated and killed the emperor Gordian III at Misikhe, defeated a large Roman force at Barbalissos, and captured the emperor Valerian in a battle between Edessa and Carrhae.[6] Res Gestae Divi Saporis. Roman sources only mention the latter battle and usually imply that Valerian was captured through treachery.
The name Res Gestae Divi Saporis was given to it by archaeologist M.I. Rostovtzeff in imitation of the emperor Augustus' Res Gestae Divi Augusti.

Inscription of Kartir in Ka'ba-ye Zartosht
1. And I, Kartir, the Magi-master (Magu-paiti = Mobed), have been shown to be of good service and loyal to the Yazads and Shahpuhr, King of Kings. For that service that I have rendered to the Yazads and Shahpuhr, King of Kings, Shahpuhr gave me authority and power in matters of the divine services at court and in kingdom after kingdom, place after place, throughout the whole empire in the magus-estate. And by the command of Shahpuhr, (2) King of Kings, and the provision of the Yazads and the King of Kings in kingdom after kingdom, place after place, many divine services in magnificence and many Warharan fires were established, and many magi became happy and prosperous, and many fires and magi were imperially installed. And Ahura Mazda and the Yazads attained great profit, while great confusion resulted for Ahriman and the devs. And for these many fires and services which are in the writing on my position thus in manner (3) Shahpuhr, King of Kings, made a testamentary instruction to the heir apparent: "Let this house be your foundation, and as you may know, that for the Yazads and us was well done, so let be done!" And in imperial documents and records that were made at that time under Shahpuhr, King of Kings, at court and throughout the whole empire in place after place, in those records it is written: "Kartir, the Herbed." And then Shahpuhr, King of Kings, to the deities' (4) throne died.
Then his son Hormizd, King of Kings, rose over the empire. And Hormizd, King of Kings, conferred on me miter and cincture and created for me a higher rank and dignity, and at court and in kingdom after kingdom, place after place, throughout the whole empire he gave me more authority and power in matters of the divine services, and created for me the title "Kartir, Ahura Mazda's magus-master" after the name of Ahura Mazda, the Deity. And thereupon in kingdom after kingdom, place after (5) place, many divine services were performed in magnificence, and many Warharan fires were established, and many magi became happy and prosperous, and many fires and magi were imperially installed. And in imperial documents and records which at that time under Hormizd, King of Kings, at court and throughout the whole empire in place after place were made, in those this was recorded: "Kartir, Ahura Mazda's magus-master." And then Hormizd, King of Kings, to the deities' throne died.
6. Then Varahran, King of Kings, son of Shahpuhr, King of Kings, and brother of Hormizd, King of Kings, rose over the empire. And Varahran, King of Kings, also held me in high honor and dignity and at court and in kingdom after kingdom, place after place, gave me authority and power for divine services of every sort. And thereupon in kingdom after kingdom, place after place, many divine services were performed in magnificence and many Warharan fires were established, and many magi became happy (7) and prosperous, and many fires and magi were imperially installed. And in documents and imperial rescripts and records which were made at that time under Varahran, King of Kings, in those also this was recorded: "Kartir, Ahura Mazda's magus-master." And then Varahran, King of Kings, son of Shahpuhr, to the deities' throne died.
Then Varahran, King of Kings, son of Varahran, who in the empire is devout and sincere and faithful (to his promises) and well behaved and beneficent, rose over the empire. And by the grace of Ahura Mazda and the Yazads and for his own (8) soul's sake he made my position of superior rank and dignity in the empire, and he conferred upon me the rank and dignity of the grandees, and at court and in kingdom after kingdom, place after place, throughout the whole empire for the divine services he gave me more authority and power than as I had before, and he made me magus-master and judge for the whole empire, and he made me master of ceremonies and powerful overlord at the fire of Anahid-Ardashir and Anahid, the Lady at Istakhr. And they created for me the title "Kartir, (9) Varahran's Soul-savior, Ahura Mazda's Magus-master."
And in kingdom after kingdom and place after place throughout the whole empire the services of Ahura Mazda and the Yazads became preeminent, and great dignity came to the Mazdayasnian religion and the magi in the empire, and the Yazads and water and fire and small cattle in the empire attained great satisfaction, while Ahriman and the devs were punished and rebuked, and the teachings of Ahriman and the devs departed from the empire and were abandoned. And Jews, Sramans (Buddhists), (10) Brahmins, Nasoreans (Orthodox Christians), (Gnostic) Christians, Maktak (Baptisers), and Zandiks (Manichaeans) in the empire were smitten, and destruction of idols and scattering of the stores of the devs and god-seats and nests was abandoned. And in kingdom after kingdom and place after place many divine services in magnificence and many Warharan fires were established, and many magi became happy and prosperous, and many fires and magi were imperially installed. And in documents and imperial rescripts and records, under Varahran, King of Kings, son of Varahran, (11) which were made, in was recorded, "Kartir, Varahran's Soul-Savior, Ahura Mazda's Magus-master."
And from earliest times onward for the sake of the Yazads and noble lords and for my own soul's sake, I, Kartir, saw much trouble and toil. And I made prosperous many fires and magi in the empire of Iran. And I also, by command of the King of Kings, put in order those magi and fires which were for the territory outside Iran, wherever the horses and men of the King of Kings arrived—the city of Antioch and the country of Syria (12) and what is beyond Syria, the city of Tarsus and the country of Cilicia and what is beyond Cilicia, the city of Caesarea and from the country of Cappadocia to Galatia, and the country of Armenian and Georgia, and Albania, and from Balaskan to the Alans' pass. And Shahpuhr, King of Kings, with his own horses and men visited with pillaging, firing, and havoc. (13) But I did not allow damage and pillaging, and whatsoever pillaging had been made by any person, those things I had taken away and returned to their own country.
And I made prominent and reverend the Mazdayasnian religion and magi who were correct within the empire, while heretical and unstable men, who within the magus-estate in matters of the Mazdayasnian religion and divine services did not observe orders, these I punished with corporal punishment (14), and I rebuked them and made of good odor. And I established many fires and magi, and executed imperial documents. And by the provision of the Yazads and the King of Kings and by my efforts many Warharan fires were established in the empire of Iran, and many kin marriages were made, and many people who had become unfaithful (to their vows), became faithful again. There were also many who had come to follow the doctrines of the devs, and by my efforts they forsook those doctrines of the devs and accepted instead the doctrines of (15) the Yazads. And many ltps'ks [1] were held. And much consideration of religion of various kinds and other divine services also became very magnificent and superior, which are not written in this inscription for lack of space.
And by me for my own house also in place after place many Warharan fires were established, and for those many fires that I established for my own house I offered for every feast, feast after feast, 1133 ltps'ks (16), and that makes for 1 year 6798 ltps'ks. And for my own house I created other divine services also, of various kinds, which, if they were written in this inscription, would have become too much.
I wrote this inscription so that in the future anyone who sees imperial records or documents or other (17) inscriptions will know that I am that Kartir who under Shahpuhr, King of Kings, was entitled "Kartir, the priestly school master," and under Hormizd, King of Kings and Varahran, (18) King of Kings, I was entitled "Kartir, Ahura Mazda's magus-master," and under Varahran, King of Kings, son of Varahran, I was entitled "Kartir, Varahran's Soul-savior, Ahura Mazda's magus-master." And whoever may see or read this inscription, may that one be to the Yazads and noble lords and himself devout and sincere, that one (just) so, as I (19) have been, in order to attain good fame and fortune for this bone-endowed body, and salvation for the soul.
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