Caves of Hella in Iceland offers guided tours of five mysterious man-made caves, with visitors exploring three caves and peering into two. The historical site, believed to be older than the Nordic Viking settlement, features ancient crosses, wall carvings, and carved seats. Visitors can ponder whether the caves were crafted by the Celts or used for ancient worship. Located near Route 1, about an hour's drive from Reykjavik, Caves of Hella provides a unique opportunity to delve into Iceland's hidden world and uncover the secrets of these historic caves.