Metlaoui is a phosphate-mining town in southwestern Tunisia, unremarkable in itself but the starting point for one of the country's most memorable experiences. The Lézard Rouge (Red Lizard) is a restored beylical train — once the private carriages of the Tunisian rulers — that runs a 40-minute scenic route through the Selja Gorge. The narrow canyon walls rise steeply on both sides, the colours shifting from red to ochre, and the slow pace of the train lets you take it all in.
The train typically runs once a day; check schedules locally as they can change. Metlaoui is an easy side trip if you are heading to the mountain oases of Tozeur or Tamerza.