ViewMaster 3 Reel Set - Caverns of Sonora, Texas - Long Card Caverns of Sonora, a National Natural Landmark, is a unique cave located 8 miles (13 km) west of the small city of Sonora, the seat of Sutton County, Texas. It is a world-class cave because of its stunning array of calcite crystal formations, especially helictites. A walk through Caverns of Sonora might be one of the most peaceful, yet awe inspiring experiences of your life. When your tour guide hits the switch to light "the first pretty part," most visitors gasp in surprise. Thereafter, each room presents a new and different display of nature's wonder. 3 ViewMaster Reels with 21 images in 3D. You will need a View-Master viewer to see the wondrous images, available here on Amazon.