Capital cities are etched with the ideologies of the empires that design them. They often present a microcosm of a leader’s intended cosmos. In misunderstanding the city, then, one runs the risk of misunderstanding the imperial project as a whole. Islamic empires, like others, looked to the stars to imbue their capitals with meaning and purpose.
In 750 CE, the Abbasid dynasty overthrew the Umayyads, wresting control of the caliphate from the family that had held it for nearly a century. The Muslim world was under a new authority. Knowing that the defeated Umayyads had established Damascus as their center of power, the newly crowned Abbasids set about building a new capital city. In 762 CE, al-Mansur—the new caliph of lands stretching from Tunisia to northern India—would found Baghdad, the City of Peace. To fashion a capital whose greatness would be etched among the stars, he turned to astrologers versed in the ancient science.
Today, in the United States and Europe, astrology is often dismissed as a pseudoscience, rather than recognized as a field with a deep history and broad application. And yet, the importance of astrology to medieval and early modern Muslim empires is beyond doubt. Consequently, an understanding of this tradition is essential for mapping the beliefs, decisions, motivations, and dimensions of the Islamic world.
The use of astrology tells us of these dynasties’ desires to forge something truly universal and uncovers the methods they used to etch their ideologies onto their cities. Baghdad, Cairo, and Ahmedabad are all a testament to the vast intellectual curiosity of medieval Muslims—their ability to integrate the ancient, pre-Islamic past into their contemporary Islamic society, and the splendor they translated from the stars into their city plans.
The decision to move the capital of the caliphate from Damascus was not taken lightly. Like the Umayyads before them, the Abbasids chose to shift the center of power within the empire. Unlike their predecessors, however, the Abbasids chose to build a new capital rather than settle in an already established city. Al-Mansur saw an opportunity to create a city shaped for the purpose of proclaiming God’s glory to the world—and, by extension, the glory of the Abbasids themselves.
Figure 1: Map of the Early Islamic world via the al-Ṯurayyā Project.
He settled on ancient Mesopotamia, selecting land near Ctesiphon, the capital of Persia’s Parthian and Sasanian empires, to house his new city. The location signaled to the world not only the birth of a new empire, but one forged from the fragments of antiquity.
To ensure the glory of the new capital, al-Mansur enlisted the aid of astrologers versed in the venerable science of the stars: Nawbakht and Mash’allah ibn Athari would work to bring their caliph’s vision to light. Theirs was a city plan that enshrined divine intent. Nawbakht was of Persian descent, claiming lineage to the dynasties of the old Persian empires. Mash’allah was of Persian Jewish descent. Both were experts in the style of astrology popularized by Hellenistic writers like Ptolemy, Valens, and Dorotheus of Sidon.
Together, Nawbakht and Mash’allah employed a branch of the science known as “electional astrology,” in which the practitioner would “elect” an auspicious moment, based on the placement of the planets, to begin an endeavor. Medieval Muslims were deeply drawn to this style of astrology, so much so that they scheduled many of their ordinary activities—from haircuts to sex—based on astrological timing. One widely read text warns its readers to avoid such activities when the moon is in Scorpio. Ibn al-Nadim, the famed bibliographer and bookseller, attests to the popularity of such instruction manuals.
This popularity evinces the widespread acceptance of this ancient science and the productivity of astrological writers during this period, but it also—and equally significantly—demonstrates the accessibility of astrology. Texts written by astrologers like Abu Ma’shar took what had once been the preserve of the priestly and elite classes, in the Hellenic world, and opened its secrets to other literate classes. Astrology, like other forms of learning, became one way in which Muslims, Christians, and Jews of the empire could experience social mobility, in a society that prized learning.
The use of astrology in the premodern Islamic past can help us trace the complex cosmologies and politics of Muslim dynasties.
The impulse to synthesize a pre-Islamic past into a Muslim present originated in the founding of this new capital city. The founding of Baghdad would initiate for Abbasid society a period of deep and critical engagement with the past. Muslim thinkers, philosophers, and scholars sought to preserve, expand, and rethink ancient knowledge. The integration of past and present mirrored the integrative social fabric of Abbasid society. Al-Mansur’s astrologers were Persian and Jewish, reflecting the cultural and religious diversity of the empire. The new city was not designed according to a specific religious perspective, but according to the pre-Islamic science of astrology, a tradition born in Mesopotamia and fused with Egyptian characteristics by Hellenistic astrologers in Alexandria.
The Abbasid dynasty forged their capital—and subsequently their empire—as a truly universal site, one in which the pre-Islamic past was drawn, preserved, and integrated spatially and intellectually. Consequently, the new city would become the home of Muslims, Jews, and Christians alike, with Arabs, Persians, Africans, and Greeks living side by side.
Figure 2: An illustration from the 15th-century book of the birth of Prince Iskandar, grandson of Tamerlane. This is a horoscope for the moment of Iskandar’s birth, on April 25, 1384. (Image from the Wellcome Library via Wikimedia)
Foundation dates can establish the path to fortune for a person, event, or place. We are told by later scholars Yakut (a 13th-century geographer) and al-Biruni (an 11th-century scientist) that Nawbakht and Mash’allah selected July 30, 762 CE as the astrologically auspicious moment to break ground for the new capital. The astrological chart for this moment etches onto the project the ideology that al-Mansur hoped to convey to the world: Shams (the sun) was in al-Assad (Leo), its home among the zodiac and one of the kingly signs. Meanwhile, Mishtari (Jupiter), the planet of wealth and learning, was rising over the horizon in al-Qaws (Sagittarius). The timing of such events required careful calculations, advanced understanding of observational astronomy, and complicated geometry. This elaborate process and technical achievement were a not-so-subtle demonstration of the Abbasid caliphate’s high intellectual culture. The city was to be their empire of the mind made manifest.
Whether the elected moment was truly auspicious or not was less important than what the chart represented for its commissioner: it was a promise, a declaration of what Baghdad would be as a capital—the Queen of Cities, a place of glorious wealth and learning. The city’s layout, too, reflected the celestial aspiration of its founders. It was designed as a series of concentric rings, reflecting the ordered heavens imagined in Islamic cosmology.
Figure 3: The “Round City” plan of Baghdad in the time of al-Mansur, reconstructed by Guy Le Strange (1900). (Image via Wikimedia)
Within a generation, Baghdad would go on to become the center of the Islamic world, the heart of its intellectual, cultural, and political life. The descendants of al-Mansur would build the Bayt al-Hikmah: a massive library-like institution dedicated to the preservation, translation, and expansion of ancient knowledge. Here, Muslim scholars, Jewish sages, and Christian scribes would expand the frontiers of knowledge—from Greek science to Persian medicine to Indic numbers—under the direction of their Islamic patrons. For 500 years, Baghdad would be a center of learning.
When the fourth Fatimid caliph, al-Mu’izz, established a new capital in North Africa, he, too, would turn to astrologers, seeking to build a city to rival Baghdad. His court astrologers stretched out a great rope with bells on it and raised their astrolabes to the heavens, awaiting the perfect moment to ring the bells and signal the breaking of ground. Unfortunately, at the most inauspicious moment, a crow landed on the rope, sounding the signal prematurely. As the workers began digging, the astrologers looked up and—in horror—realized the planet of war, al-Mirrikh (Mars), was rising. One of the astrologers rushed forth, shouting, “Al-Qahir, al-Qahir!” (“the Vanquisher, the Vanquisher!”— another name for the planet). The caliph, however, took this sign to heart and named the city after Mars: Al-Qahira, or Cairo.
Figure 4: Horoscope for the founding of the city of Baghdad, according to data provided by Yakut and al-Biruni, based on Holden. (Image created by Ali A. Olomi).
Caliph al-Mu’izz, a conqueror, thus adopted the name of the planet of conquest as the name of his capital city. This story, likely apocryphal, speaks to the importance of the capital cities of the Islamic world, and the way in which their founders employed astrology as a means of conveying their ideology. Whether Mars was truly rising as Cairo was founded is not clear—but we do know that al-Mu’izz and his followers took astrology seriously. If he were to create a capital to rival Baghdad, then he, too, would rely on astrological symbolism.
Later, when the Gujarat sultanate established Ahmedabad, in what is now western India, they also used horoscopes to determine an auspicious moment for its founding, in order to etch onto their capital the symbolism of the heavens. Historian H. G. Shastri notes that the records preserve competing dates for the foundation of the city, but all attest to the importance of the horoscope for breaking ground.
The competing dates may have been a result of the Mughals’ reliance on both Muslim and Hindu astrologers, with each camp using slightly different mathematic divisions of the zodiac. Yet, the weight given to both traditions of astrology indicates how the Mughals—like the Abbasids before them—incorporated pre-Islamic knowledge into their societies. Astrology in India has ancient roots, predating the Mughals; as such, Hindu experts were afforded a position alongside Muslim astrologers. As in previous empires, astrology’s diverse traditions would be welcomed at the Islamic court.
The use of astrology in the premodern Islamic past is a crucial intellectual thread that can help us trace the complex cosmologies and politics of Muslim dynasties. It also tells us of these dynasties’ desires to forge something truly universal. When medieval and early modern Muslim empires designed their cities, they turned to the heavens for inspiration, bringing ancient pre-Islamic knowledge into their Muslim societies, thus designing something timeless.
This article was commissioned by Stephanie Wong and Sarah E. Bond. 
Featured Image: Annotated diagram of the phases of the moon by Al-Biruni, circa 10th century / Library, Museum and Document Center of Iran Parliament (Wiki Commons – Public Domain)