Spiritual pilgrimages, religious retreats and other faith-based journeys comprise one of today’s fastest-growing travel markets, according to the World Tourism Organization. The first International Conference on Religious Tourism estimated it to be an $18 billion industry worldwide. A Travel Industry Association of America survey found that one in four travelers said they were currently interested in taking a spiritual vacation, and the interest is spread evenly among all adult age groups.

Packaged tours embrace everything from formative Christian destinations to sites sacred in Buddhist, Hindu, Islam and other ancient religious traditions. The oldest known pilgrimage site is said to be Mount Kailash, in Tibet, a holy travel destination for about 15,000 years. Those not up to the physical demands of travel can alternatively take advantage of the growing number of DVDs available online and at local libraries that allow individuals to take “armchair” pilgrimages around the world.