Mosques in
Isfahan, with its
four-iwan layout dating from the early 12th century The most important religious monument from the Great Seljuk period is the
Jameh Mosque of Isfahan, which was expanded and modified by various Seljuk patrons in the late 11th century and early 12th century. Two major and innovative
domed chambers were added to it in the late 11th century: the south dome (in front of the
mihrab) was commissioned by
Nizam al-Mulk in 1086–87 and the north dome was commissioned by
Taj al-Mulk in 1088–89. Four large iwans were later erected around the courtyard around the early 12th century, giving rise to the
four-iwan plan. These additions constitute some of the most important architectural innovations of the Seljuk period. The four-iwan plan already had roots in ancient Iranian architecture and has been found in some
Parthian and
Sasanian palaces. Soon after or around the same time as the Seljuk work in Isfahan, it appeared in other mosques such as the
Jameh Mosque of Zavareh (built circa 1135–1136) and the
Jameh Mosque of Ardestan (renovated by a Seljuk vizier in 1158–1160). The north dome of the Isfahan mosque, in particular, is considered a masterpiece of medieval Iranian architecture, with the interlacing
ribs of the dome and the vertically aligned elements of the supporting walls achieving a great elegance. Practically none of these madrasas founded under Nizam al-Mulk have survived, though partial remains of one madrasa in
Khargerd, Iran, include an iwan and an inscription attributing it to Nizam al-Mulk. Nonetheless, it is clear that the Seljuks constructed many madrasas across their empire within a relatively short period of time, thus spreading both the idea of this institution and the architectural models on which later examples were based. Godard's origin theory has not been accepted by all scholars, but it is widely-attested that the four-iwan layout did spread to other regions alongside the spread of madrasas across the Islamic world.
Caravanserais Large caravanserais were built as a way to foster trade and assert Seljuk authority in the countryside. They typically consisted of a building with a fortified exterior appearance, monumental entrance portal, and interior courtyard surrounded by various halls, including iwans. Some notable examples, only partly preserved, are the caravanserais of
Ribat-i Malik (c. 1068–1080) and
Ribat-i Sharaf (12th century) in Transoxiana and
Khorasan, respectively. File:Rabat-i Malik caravanserai 2 (cropped and retouched).jpg|Entrance portal of the
Ribat-i Malik caravanserai on the road between
Bukhara and
Samarkand (c. 1068–1080) File:نمای مقابل، از بالای رباط شرف.jpg|
Ribat-i Sharaf caravanserai in Khorasan (northeastern Iran), built in 1114–1115
Mausoleums The Seljuks also continued to build "tower tombs", an Iranian building type from earlier periods, such as the so-called
Tughril Tower built in
Rayy (south of present-day
Tehran) in 1139–1140. More innovative, however, was the introduction of mausoleums with a square or polygonal floor plan, which later became a common form of monumental tombs. Early examples of this are the two
Kharraqan Mausoleums (1068 and 1093) near
Qazvin (northern Iran), which have octagonal forms, and the large
Mausoleum of Sanjar (c. 1152) in
Merv (present-day
Turkmenistan), which has a square base. File:Kharaghan.jpg|
Kharraqan Towers, a set of mausoleums built in 1068 and 1093 in Iran File:تاریخ ری.jpg|
Tughril Tower in
Rayy, south of present-day Tehran (Iran), built in 1139–1140 File:SultanSanjarMausoleum1.jpg|
Mausoleum of Sultan Ahmad Sanjar (c. 1152) in
Merv (present-day
Turkmenistan)
Palaces and pavilions at Merv (12th century), possibly an archive or treasury While historical sources mention the Seljuk construction of various palaces in different cities, including Baghdad, the only palace of which anything remains today is the palace of
Sultan Sanjar at the now-ruined city of Merv. The large palace, located in the city's citadel (the Shahriyar Arg), contained a central courtyard surrounded by four iwans. Fragments of
stucco decoration found around the site suggest that it was probably richly decorated. Nearby, within the same citadel, is a rectangular building with massive walls marked by rounded
buttresses and no windows. It has been tentatively identified as an archive or treasury. The citadel would have included – in addition to his mausoleum – other buildings and amenities such as a mosque,
bathhouse, barracks, and
mint. The palace itself was probably also surrounded by gardens, fountains, and pools, as most likely were other Seljuk palaces. Seljuks sultans and their courts were often on the move and, even when visiting a city, might have resided in tents within a military camp in the countryside. The sultans also built and visited pavilions (
kūshks) in the countryside or suburban parks outside cities. They are known to have existed around the Seljuk capitals of Isfahan and
Hamadan. Some remains of them are still found around Merv. The latter were lightly fortified and consisted of two-story structures, with the ground level used as a cellar or other practical purpose while visitors enjoyed the upper level. They were probably surrounded by gardens and possibly other buildings. == Materials and decoration ==