For seven centuries, the tomb of Alexander the Great was held in highest esteem at the center of Alexandria, Egypt. Then it was obliterated without a trace, and not even a written reference to its destruction has survived to our days. The fate of the tomb of the world's greatest conqueror—and of his embalmed body—is a baffling blank spot in history.

Thirty years ago, camel racing was thought to be a way of keeping the "ship of the desert" out of history's drydock. Now, it is a popular sport in the United Arab Emirates. Champion camels are celebrated in poetry and song, and racing-driven research is bettering camel bloodlines, promising benefits that extend beyond the track.

From a well filled in some 1900 years ago, a young Saudi handed Tom Barger an inscribed slab—known now as the "Hadrian stele"—that has helped redraw the map of the Roman army's reach into the Arabian Peninsula. In April, a ceremony in Riyadh marked its return, and that of the rest of the Barger Collection, to Arabia and Saudi Arabia's National Museum.

The Moroccan city of Fez has been likened to a geode, filled with glittering crystals of art and architecture. Among its brightest refractions are the geometric tile works known as zillij, which grace homes, shops, schools, mosques and streets. Much of the best zillij has been made by members of the last five generations of the Benslimane family, which has recently opened its first branch store—in lower Manhattan.