In almost any condition, China’s Tianmen Shan looks otherworldly, like a portal to something greater than the Earth.

Usually shrouded in blinding sunlight or dense fog, visitors climb 999 steps to reach the peak, where they end their trip 4,100 feet up, in a realm where legend believes the gods meet the mortal world.

420 feet high and 180 feet wide, the cave slit of the “Gateway to Heaven” is visible from any distance below the cave. The exhaustive hike up the hill follows an old path of carved stone stairs, dotted with small wooden huts. The entire path is guided by the portal at the peak, but the views on the way up make it obvious why generations of people in Hunan believed that Tianmen Shan was the realm of the gods.