GOBEKLI TEPE, Turkey — Tour guide Sabahattin Alkan herds curious tourists through the scorching afternoon heat, luring them with the promise of something far stranger than your typical vacation snap. "Over here on the right, you see a spaceship landed recently," he says with a grin. He's joking. Mostly. But more on that in a minute. We're in the Urfa plain, a dry, dusty stretch about 25 miles from the Turkish-Syrian border. That "spaceship" is actually just a curved roof. But what lies beneath the dome has sparked decades of mystery, curiosity — and conspiracy. One of the T-shaped pillars...