This monumental domed chamber, known locally as Zindan-i Iskandar (Alexander’s Prison), is situated at the center of the old city of Yazd, in the historical Fahadan neighborhood and in the vicinity of the eleventh-century Davazdeh Imam Shrine. The Zindan-i Iskandar takes its name from the legend that Alexander built a castle in this region as a prison for captive princes. In some literary works, the city of Yazd is also referred to as "Zindan-i Iskandar".
Historical sources suggest that the mausoleum and its adjoining structure are the remains of Madarasa Ziaiyya, a religious school patronized by Ziya' al-Din Husayn-i Razi and his sons, scions of a local notable family, in the second half of the thirteenth century (the Il-Khanid period). In the compendium Tarikh-i Jadid-i Yazd (The New History of Yazd), a ninth-century author relates that the madrasa had a high portal with tall minarets and was surrounded by prodigious mansions with tall wind-catchers (badgirs), all built by the members of the same family. Nevertheless, as Iraj Afshar has pointed out, the identification of the building as the Madrasa Ziyaiyya is not utterly verifiable, as there is no epigraphic evidence in the building to support this proposition.
Similar to the typical plan of the madrasas of the thirteenth and fourteenth century, the existing building consists of a rectangular courtyard surrounded on three sides by elevations containing iwans; probably the now-vanished eastern elevation had an iwan that has not survived. The western iwan is larger than the northern and southern ones, which are similar in size and flanked by rectilinear cells of different depths. The discrepancy in the shapes and sizes of the rooms surrounding the courtyard is probably the result of later modifications. At the center of the courtyard is a payab, an underground chamber that gave access to the qanat (underground water channel) that passed beneath the building.
The mausoleum is located at the southeast corner of the building, connected through two doorways to the courtyard and the main iwan. Square in plan (8.8 meters per side) and erected atop thick walls in order to support its eighteen-meter-high dome, the domed mausoleum dominates the courtyard as well as the skyline of the surrounding area.
The structure is built of mud brick, with baked brick used exclusively in the outer shell of the dome of the mausoleum. The upper part of the octagonal zone of transition is decorated with a three-tier muqarnas cornice. Unlike the courtyard and its surrounding spaces that bear no decoration, the interior of the tomb chamber is ornamented with floriated Kufic inscriptions and vegetal motifs in painted plaster, similar to other surviving tomb chambers from the Muzaffarid period.
The Zindan-i Iskandar was used for oil production until the 1970s and was in a dilapidated condition until its restoration by the National Heritage Organization of Iran, estimated to have taken place in the 1980s. Post-restoration, the building has become a major tourist destination.