The bulge in the corner of the surrounding wall is the base of the closed tower, the first of the seven that punctuate the ramparts. Massive and imposing, it looms sternly up over the main buildings to nearly twice their height, as befits its role as an indomitable stronghold.

Its irreproachably smooth cylindrical shape offers a hold only to the eyes, if that. A few minute slivers of shell on the surface latch onto the sun's rays and enliven its otherwise dull façade with fleeting sparks.

Yet you are intrigued by something else: the apparent lack of any kind of door or window. Not the slightest opening anywhere. Of course, you can only see one side of the tower, but the other is much the same.

Without much hope, you look for an entrance but are already aware that you will not be able to visit. The closed tower is not to be entered. It offers no staircase or practicable room. Perhaps there is a chamber somewhere between its walls that you will never see, isolated at the heart of this pillar of sand. Or perhaps there is no room and the tower is entirely solid from floor to roof.

No matter.

You have six more towers to see.

Go through the portico to your right and down the stairs.