Southeastern Morocco has an unusually dense concentration of ruins. As we drove through the Dadès and Draa valleys, we spotted countless crumbling rammed-earth buildings dotting the countryside. They ranged from lonely houses surrounded by nothing but rocky desert to complex ksour (fortified towns; “ksar” is the singular) with walls, gates and towers. Most were long since abandoned and slowly melting back into the earth, yielding to rare but damaging rains. I suspect that none but the most famous of these ruins will survive the next 50 years.

Ait Ben Haddou

Climbing the side of a mesa along the Asif Ounila River, this magnificent ksar dating back some 400 years is in no danger of disappearing: it draws buses of tourists every day. It has also been preserved for posterity in numerous films, including “Gladiator,” “Alexander” and “Babel.” From afar, Ait Ben Haddou looks like an apparition from another era, a cluster of cubic mud-walled buildings above a valley verdant with olives, palms and cypresses. Terraces inside the ksar afford magnificent views of its towers — some restored, some collapsing — backdropped by the shimmering valley. The main route up to the mesa’s panoramic top is crowded with tourists, but even in busy Ait Ben Haddou, it’s possible to find quiet side streets.

Skoura

The valley around this once-important caravan stop contains innumerable old kasbahs (fortified mud-walled structures), with towers in various states of disrepair rising above the palm groves. Our guide took us inside one of the abandoned buildings, which had a layout almost identical to the kasbah of Dar Ahlam. “People own this kasbah,” he explained, “but too many people own it, and no one wants to pay for repairs. Also, no one wants to live in a building like this anyway.” We also visited the restored Kasbah Amridil, large enough to rank as a small ksar, where we got a better sense of how kasbah interiors looked. Some of the reed ceilings were original, and some of the walls still bore black smoke stains.