Day 90: El Haddej to Sousse
The industrial port of Sfax is signalled by a plume of black smoke trailing out across the Mediterranean, and for several miles we pass through a wasteland of spoil heaps and phosphate factories. I couldn't help noticing the name of the road: Boulevard de l'Environment.
By lunchtime we have reached El Jem and are able to eat beside one of the finest sights in Tunisia, the honey-coloured walls of the third biggest amphitheatre the Romans ever built.
It's a powerful presence. Fourteen hundred feet in circumference, it could accommodate over 30,000 spectators.
Gazing unhurriedly at it over a lamb kebab, I'm struck by the boldness of the design. The massive blocks of stone not only had to be hauled in from quarries 20 miles away, they also had to be stacked in an elliptical wall 100 feet high, supported entirely by its arches. No buttressing, no concrete, just a precisely calculated balancing act.
El Jem itself is a modest market town, whose entire population could fit in one end of the colosseum, and, like flies round an elephant, the locals get on with life apparently oblivious to the monster in their midst.
Choose another day from Sahara