Cathedral Caverns State Park is located near the town of Grant, in northeastern Marshall County. The limestone caverns were formed around 350 million years ago. The massive entrance is 128 feet across and 25 feet high, making it the largest natural commercial cave opening in the world. The largest chamber, known as the Big Room, includes a soaring ceiling, with dramatic stalactites and stalagmites, that look “like a cathedral.” It was declared a National Natural Landmark in 1972.
