Natural Bridge State Park has a natural sandstone arch created by the eroding effects of wind and water. Family near rock arch A sign tells about the ancient rock shelter. Wisconsin Department of Tourism Photo The natural bridge has an opening 25 feet high by 35 feet wide. This weathered formation, located in Wisconsin's Driftless Area, was missed by the glaciers during the last Ice Age. Near the bridge is a rock shelter used by people when the glacier was melting, 11,000 years ago. The park, established in 1973, totals 530 acres including a 60-acre state natural area. Winding through part of the natural area is a self-guiding nature trail with information about Native Americans' uses of plants. There's a 2-mile hiking trail through the woods south of the highway. Climbing on the arch itself or going into the shelter are prohibited to protect the natural area.