Two hours from the neon-bright bustle of contemporary Japan looms Koyasan, the birthplace of Shingon Buddhism and a place of such mysterious, otherworldly power that visiting it feels like stepping out of time. Pico Iyer immerses himself in the life of one of the country's last traditional refuges, where every inch is sacred and ghosts of old Japan lurk in every shadow

Barely twenty people got out when at last the small country train reached the final stop on the line: Gokurakubashi, or the Bridge of Heaven. We disembarked and stepped into a cable car that slowly clanked up a thickly forested slope of pines: a handful of Western couples, an intrepid Japanese matron or two, and I. For five minutes we rose high, high above the woods below, until we were deposited in a clearing about 2,800 feet above sea level. A largely deserted parking lot lay in front of us, and a mountain road so narrow that two buses could not pass at the same time.

Beyond taxis and buses, no vehicles are allowed on the road, I had read. For more than a thousand years, in fact, no woman had even been permitted to ascend the holy mountain. When the mother of the mountain's discoverer, Kobo Daishi, tried to climb the slopes, she was repelled by a "thunderstorm of fire rain."

I took a quiet bus around the curves—there is nothing here but trees, the outlines of temples, and a few walking trails on which yellow signs note the imminence of bears. Then, five minutes later, I got off on the solitary main street of Koyasan. A five-minute walk away to one side of me was a majestic temple complex; ten minutes to the other was the Ichi-no-hashi Bridge, where monks and pilgrims traditionally wash their hands and faces before entering what they believe to be the "pure land," or paradise, of Shingon Buddhism. Across that bridge was a dense grove of giant cedar trees, many of them eight hundred years old, surrounded by more than 200,000 graves. And at the very end of the path lay the mausoleum of Kobo Daishi, the "mother of Japanese culture," as the pamphlets describe him, though to us he might better be identified as a founding father (or all the founding fathers combined, since he seems to bring together in one person the merits of George Washington, Thomas Jefferson, and Benjamin Franklin).

Around me in the little town were more than a hundred temples, their high-flying cypress-bark roofs like the prows of seagoing vessels about to sail off into the mist. The air was decidedly cooler than in the blazing Osaka I'd left just two hours before—twenty degrees cooler, I would learn—and although the sun was still in its late summer splendor in the cities of the plain, here, the maple leaves were beginning to turn, six weeks earlier than they would down below, and there was already a sense of coming snow. The holiest place in Japan, as Koyasan is called, offered a sense of solemnity, of gravitas, of overwhelming darkness that I could not remember seeing in my twenty years of living in the country.

You could best say what Koyasan is, in fact, by saying everything it isn't. There are no high-rises on the sacred mountain, no fast-food parlors, no karaoke bars or pinball arcades. There is none of the flash and acceleration of the neon-streaking, crowded, wildly clangorous shopping malls and entertainment complexes that make up the fabric of modern Japan. Mount Koya (as the name would be in English) is consecrated to everything old and changeless and hushed.