era." The Ka'ba-ye Zartosht is a beautiful structure: its proportions, lines and external beauty are based on well-executed architectural principles. Currently, the structure is part of the Naqsh-e Rustam compound and owned by the Cultural Heritage, Handicrafts and Tourism Organization of Iran. Name Alireza Shapur Shahbazi believes that the phrase Ka'ba-ye Zartosht is relatively new and inaccurate, originating around the fourteenth century. When the structure was discovered by the Europeans, its local name was Karnaykhaneh or Naggarekhaneh; the Europeans considered it a special site for worshiping fire, since the inside of the structure was blackened by smoke, and because they mistook the Zoroastrians for fire-worshipers, they attributed the place to them and named it the Zoroastrians' fire temple. As the shape of the structure was cuboid and the black stones that were placed on the white background of its walls resembled the Black Stone, the Muslims' Kaaba, it became famous as Ka'ba-ye Zartosht, the Kaaba of Zoroaster. The Encyclopedia Iranica explains about the name of the structure: "Ka'ba-ye Zartosht has probably acquired its name in the fourteenth century, the time that the ruined ancient sites in the whole Iran were attributed to characters in the Quran or Shahnameh. This does not mean that the place has been Zoroaster's mausoleum and there is also no report of the pilgrims' travels there for pilgrimage." Due to the discovery of Kartir's inscription on its walls, it is revealed that the name of the structure in the Sasanian era was Bon Khaanak, meaning the Cold Foundation, as the inscription reads: "This Cold Foundation will belong to you. Act as the best way you see suitable that will delight our gods and purpose (implying Shapur I)." There is no knowledge of the name of the structure in any earlier periods. Ibn al-Balkhi has mentioned the name of the area of Naqsh-e Rustam and its mountain as Kuhnebesht, and has considered that the reason behind its naming was that the book Avesta was held there. The word Dezhnebesht or Dezhkatibehs might have also been used for the Ka'ba-ye Zartosht. Attributes Ka'ba-ye Zartosht is cuboid in shape, and has only one entrance door, which leads inside its chamber by means of a stone stairway. There are four blind windows on each of its sides. The stone used is white marbly limestone, and there are dentate shelves of black stone on its walls. The limestone blocks were brought