Abu Jafar al-Mansur

Abu Jafar Abd Allah ibn Muhammad al-Mansur was the second caliph of the Abbasid dynasty, succeeding his brother Al-Saffah in 754. Regarded by historians as the true founder of the Abbasid imperial state, he consolidated central administration, established an efficient taxation and postal espionage system (barid), and created stable imperial finances.

Al-Mansur's most momentous achievement was founding Madinat al-Salam (the Round City of Baghdad) on the banks of the Tigris in 762. Commissioning Jewish and Persian astronomers Naubakht and Mashallah to calculate the astrological foundation date, his circular city of concentric walls, palaces, and waterways became the vibrant intellectual and commercial hub of the world for five centuries.