A proposed map of the fabled Round City of Baghdad drawn up by the British orientalist Guy Le Strange in his 1900 publication
Baghdad during the Abbasid Caliphate:
As no trace of the Round City survives today, and no archaeological excavations have as of yet been conducted at the probable site in modern-day Baghdad, Le Strange drafted this map on the basis of several Arabic literary sources, all of which date to the period after the Round City declined and deteriorated. I was surprised to learn that it only remained the centre of Abbasid Baghdad for a period of roughly 50 years (AD 763-813), after which it was largely abandoned by the dynasty following the infamous civil war of the two brothers, Al-Amin and Al-Mamun, with court life in Baghdad shifting across to the east bank of the Tigris.
In terms of the Round City's location in modern-day Baghdad, Le Strange states that the
shrine of Maruf al-Karkhi "lay outside the Basrah Gate of the Round City" (#5 on the map above in the southeast corner of the Round City), and suggests that, given his estimated distances of 2,500 yards from gate to gate around the external wall (so a circumference of 10,000 yards), and 3,200 yards diameter for the Round City as a whole, we can get a very good idea of its fixed location.