Millions of faithful descend on Mexico City each year, at first by bike or by foot and then often crawling on their knees. Photographer Kike Arnal documented the sacred journey, distilling the epic-scale movement into intimate scenes that speak to the powerful motivation of faith. Arnal’s interest in the project began with a desire to photograph emotional faces, but his images also reveal deeper insights about a profound act of mass devotion.

Built more than 2,000 years ago, Petra was once a thriving city and critical trade hub. And then it faded into obscurity. National Geographic ventured to the ancient oasis in the early 20th century to explore the impressive remains of the desert city, seeing sites like the Pharaoh's Treasury and the “most striking gateway to any city on our planet.” Step back in time and see the ruins shortly after it was rediscovered.

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