[6] Under the Umayyads the Arab empire continued to expand, eventually extending to Central Asia and the borders of India in the east, Yemen in the south, the Atlantic coast of what is now Morocco and the Iberian Peninsula in the west.

[7] The empire was tolerant of existing customs in the conquered lands, creating resentment among those looking for a more theocratic state.

[1] Most buildings in Syria were of high quality ashlar masonry, using large tightly-joined blocks, sometimes with carving on the facade.

[9] Umayyad architecture is distinguished by the extent and variety of decoration, including mosaics, wall painting, sculpture and carved reliefs with Islamic motifs.

For example, the walls at Qasr Mshatta are built from cut stone in the Syrian manner, the vaults are Mesopotamian in design and Coptic and Byzantine elements appear in the decorative carving.

[10][1] The horseshoe arch appears for the first time in Umayyad architecture, later to evolve to its most advanced form in al-Andalus.

[11] The sanctuary of the Dome of the Rock, standing on the Haram al-Sharif (Temple Mount) in Jerusalem, is the oldest surviving major Islamic building.

[7][12] It is also an exceptional monument within the context of Umayyad and wider Islamic architecture, in terms of both its form and function.

[2] It was not a mosque but rather a shrine or commemorative monument, likely built to honour ancient religious associations with the site such as the creation of Adam and Abraham's sacrifice.

[13] In Syria, the Umayyads preserved the overall concept of a court surrounded by porticos, with a deeper sanctuary, that had been developed in Medina.

[3] In Syria, churches were converted to mosques by blocking up the west door and making entrances in the north wall.

[3] The minbar also began appearing in mosques in cities or administrative centers, a throne-like structure with regal rather than religious connotations.

[6] The prayer hall has three aisles parallel to the qibla wall, a common arrangement in Umayyad mosques in Syria.

[19] The marble window grilles in the great mosque, which diffuse the light, are worked in patterns of interlocking circles and squares, precursors to the arabesque style that would become characteristic of Islamic decoration.

[20] Vast portions of the mosque's walls were decorated with mosaics, of which some original fragments have survived, including some that depict the houses, palaces and river valley of Damascus.

[25] Similar to the Dome of the Rock, built earlier by Abd al-Malik, vegetation and plants were the most common motif, but those of the Damascus mosque are more naturalistic.

[25] In addition to the large landscape depictions, a mosaic frieze with an intricate vine motif (referred to as the karma in Arabic historical sources) once ran around the walls of the prayer hall, above the level of the mihrab.

[26] The only notable omission is the absence of human and animal figures, which was likely a new restriction imposed by the Muslim patron.

[a] This may be explained by construction of underground cisterns in the Abbasid period, causing the original structure to be narrowed.

[9] 38 examples of these have been discovered so far and have provided modern scholars with important evidence about Umayyad material culture and court life.

[33] The fortress-like plan was derived from Roman forts built in Syria, and construction mostly followed earlier Syrian methods with some Byzantine and Mesopotamian elements.

[32] The palaces had floor mosaics and frescoes or paintings on the walls, with designs that show both eastern and western influences.

Inscriptions below in Arabic and Greek identify the first four as the rulers of Byzantium, Spain (at that time Visigothic), Persia and Abyssinia.

Qasr al-Hayr al-Sharqi is about 100 kilometres (62 mi) northeast of Palmyra on the main road from Aleppo to Iraq.