The Grotto of the Redemption is a religious monument located in West Bend, Iowa, in the Roman Catholic Diocese of Sioux City. A conglomeration of nine grottos depicting scenes in life of Jesus, the Grotto contains a large collection of minerals and petrifications and is believed to be the largest grotto in the world.
Religious - Christianity, Objects - Roadside Attractions
It is also "considered to be the world's most complete man-made collection of minerals, fossils, shells, and petrifications in one place." The total value of all the rocks and minerals which make up the Grotto is over $4,308,000. Over 100,000 people visit the Grotto each year.