Oya History Museum — Underground Stone Cathedral

The Oya History Museum is built into a former underground stone quarry where Oya Stone — a light, porous volcanic tuff unique to this region — was mined from 1919 to 1986. The quarry excavated 30 meters underground, creating vast cathedral-like chambers with 20-meter-high ceilings, geometric columns, and sheer stone walls. The space is cold (10°C year-round), silent, and surreal — industrial archaeology rendered as unintentional art.

Oya Stone was widely used in Meiji and Taisho-era architecture (including Frank Lloyd Wright's Imperial Hotel in Tokyo) because it is lightweight, easy to carve, and fire-resistant. The quarry operated for 67 years, extracting over 1 million tons of stone using hand tools, then dynamite, then modern machinery. Today, the chambers host art installations, concerts, and film shoots (scenes from 'Rurouni Kenshin' were filmed here). Walking through the quarry is disorienting — the scale, darkness, and silence create an atmosphere closer to a cathedral or tomb than a museum.