I recently came across the term “dark tourism,” for the first time and was more than a bit surprised. According to the Dark Tourism Forum, it is “the act of travel and visitation to sites, attractions and exhibitions which has real or recreated death, suffering or the seemingly macabre as a main theme.” To me, when I thought of this, Severus Snape, the dark wizard from Harry Potter immediately sprang to mind as the poster child of “dark tourism.” I could just picture him digging around graveyards, poking around medical-specimen museums, glorying in haunted houses, touring former prisons, and thrilling to sites of mass horror, like the spot of the former World Trade Center or the bloody battle fields of the Civil War.

Travelers have always followed guidebook advice religiously, scurrying from one historic site to the next, but for some Americans the book they’re taking their cues from has changed. Move over, Frommer’s. It’s the man upstairs’ turn.

Menlo Consulting Group found in a recent survey that one-third of Americans who travel abroad said they hoped to take a faith-based trip in the future and 9.5% of travelers polled had already completed a religious journey. This percentage encompasses 4.5 million travelers and means big business for travel companies, particularly those offering guided tours of holy sites around the world.