The town of Douz has grown up around a large palm oasis that stands on the northern fringe of the Sahara. Surrounded by little other than desert and dry scrub land, historically it was an important stop on the trans-Saharan caravan routes. Today tourists come in numbers, many on organized coach tours from the coastal resorts, to get a taste of the mighty Sahara for themselves.
By car, Douz is about 1hr30m drive west of Matmata on a good road, or 2hr to the east of Tozeur. Much of the drive from Tozeur is along a causeway that crosses the Chott El-Jerid, a vast lake covered in a thick crust of dried salt.
Through the main square, where all the tourist wares are on display, and into the small bustling local market for fruit and veg, dates and olives, bread etc for your daily picnic.
You can find good restaurants and cafés in Douz, (e.g. café of glissia "grandes dunes in "zone touristique"") or eat in hotels. There are 6 large hotels in Douz in the tourist zone, or you could even go into the desert and make the sand bread "Mella" with dates!
If you take an overnight camel trek, you will get to sleep out in the desert (and hence save the cost of a night's accommodation!). Be warned though - despite pictures in the tour offices of luxury Bedouin style tents, in practice the shelter is somewhat more basic and bathroom facilities may be somewhat primitive. Still, it is a great experience with campfire, ad hoc drumming/dancing sessions, fire-baked flat bread for breakfast and camel treks back to town the following morning.