Ar imression

Ar, city of location the largest, most populous, and most luxurious city of Gor. A city of lofty cylinders, spires, towers, lights, and high bridges lit by lanterns connecting many of the towers. Surrounded by great walls, its great Gate opens onto the Viktel Aria and there are forty other gates as well. Her politics lack the grandeur of the city itself. The powerful of Ar contributed to a disaster in the delta by not supporting their own army against the invading forces of Cos. Her citizenry burned their gates and tore down their walls to aid the Cosians. Those Warriors who were betrayed by their city returned to it; their goal to liberate Ar by whatever means to revenge her humiliation and regain the glory that was hers.

Urbar's tower

Ar is the largest city of known Gor, larger even, I am sure, than Turia, in the far south. She has some forty public gates, and I suppose, some number of restricted smaller gates, secret gates, posterns, and such. Long ago, I had once entered the city through such a passage. 
Book 25, Magicians: pg 9

"Yes," said the Older Tarl, "And there," he said, poking downward with his finger, "is the City of Ar, hereditary enemy of Ko-ro-ba, the central city of Marlenus, who intends to be the Ubar of all Gor." 
Book 1, Tarnsman: pg 64

These wholesalers usually distribute to retailers, in their individual cities, or, often also, in well-known slaving centers, of which there are many for example, Ar, Ko-ro-ba, Venna, Vonda, Victoria, on the Vosk, Market of Semris, Besnit, Esalinus, Harfax, Corcyrus, Argentum, Torcadino, and others. 
Book 22, Dancer: pg 102