For nearly 180 years, both the church and the town of Saint-Denis have been without that landmark steeple. Damaged by storms, it was dismantled in 1847, supposedly so it could be built back better.

Off the coast of Marseille, National Geographic Explorer Jacques-Yves Cousteau hauled up thousands of ancient clay vessels—and showed what fantastic discoveries modern scuba gear made possible.

Years after Louis XVI and Marie-Antoinette met their fates at the guillotine, Karl-Wilhelm Naundorff convinced members of the French aristocracy that he was the royal couple’s long-lost progeny. Some ...