Pyongyang's subway—built some 316 feet belowground—is among the deepest transportation systems on the planet. And yet the 17-stop network has long been like most everything in North Korea: a complete mystery to the outside world. So much so, in fact, that some foreigners believed the subways were an elaborate hoax peddled by a government attempting to legitimize itself. Yet over the past year, North Korea has opened its full metro system to tourists for the first time, which is why Hong Kong–based photographer Elaine Li made the trip. What Li discovered beneath the capital defied expectations. “Although the stations are very dimly lit, the interiors are extremely ornate,” she says. “You see chandeliers on the ceilings, marble pillars, and of course, paintings of [former Supreme Leader] Kim Jong-il.” AD tours Pyongyang’s never-before-seen subway system for a peek inside one of the least-known countries in the world.