Foundation of Baghdad (Madīnat al-Salām)

After a year of surveying the Sawād, the caliph al-Manṣūr fixed on the west bank of the Tigris, where the rivers and canals knot together, and in 145 AH broke ground on his Round City — officially Madīnat al-Salām, the City of Peace, though the village name Baghdad refused to die.

The perfect circle of walls with four equidistant gates held the palace and mosque at its centre; within a century the city around it was the largest in the world outside China, and its paper markets, observatory and translation movement made "Baghdad" a synonym for learning itself — until the entry this database records at 4 Ṣafar 656.

The chronicles preserve the astrologers' election of the moment but no usable civil date; the year stands.