YOU NEVER KNOW what you’ll find when you go bicycling in Beijing. Eight years ago, the Belgian entrepreneur Juan van Wassenhove set off from his home in the Chinese capital to pedal around the vanishing hutongs, the labyrinthine alleyways that were once the heart of the ancient city, when he glimpsed what appeared to be the tip of a stupa rising above slate-gray roofs. After shouldering open an iron gate, he was amazed to discover a derelict wooden temple with a beautiful double-level main hall crafted by artisans in the Qing Dynasty—a rare architectural treasure. “That day I found my mission,” he recalls.