Well, we are in the left (looking south) portico of the colonnaded street. It runs for 2 kilometres, and originally had 1200 columns. 400 now stand thanks to gifts from the entrepreneur Osmane Aidi, owner of the Cham chain of hotels you come across in many towns. The Bradt Guide describes how it would be lined by porticoes with upmarket shops installed. So imagine this to be a huge shopping street. Columns are 10 meters high, each spaced 3 meters from its neighbour.
A look through what may have been the entrance to one of those shops.