"We need civilizational dialogue, not conflict," says scholar John Esposito, who has directed Georgetown University's Center for Muslim-Christian Understanding since its founding in 1993. Today, the CMCU is at the forefront of a cautious, hopeful and vitally necessary mutual exploration of Islam and Christianity.

The science of nautical archeology has come into its own in the last 35 years or so, with much trailblazing work done in Turkish waters. But how to make it clear to non-divers what an underwater archeological site looks like, and what a shipwreck can teach us about history, trade and technology? All you need is equal quantities of imagination and hard work, and a handsome 15th-century castle.

On September 19, 1137, a group of the finest craftsmen of Córdoba, in Muslim Spain, began work on a minbar, a stepped pulpit, ordered for the congregational mosque of Marrakech, Morocco. What they produced after several years of work was recognized even then as a masterpiece and a marvel, and is today considered one of the greatest examples of western Islamic art. Thanks to a Moroccan-US conservation team, the minbar is now on public display in Marrakech.

For six millennia, the Medjay people—possibly Africa's first nomadic herders—have lived among the deserts and dry mountains east of the Nile. They created some of Egypt's oldest petroglyphs, guided pharaonic gold prospectors and kept Roman armies at bay. Today, they still trade and interact with their riverine neighbors, part of the old dialogue between the desert and the sown.