Underneath the earth’s belly, a boat ride inside a 30-million-year-old all-water cavern, Penn’s Cave, reveals nature’s most ...

The oldest known cave painting on Earth is not a charging bison in Europe but a reddish pig on a limestone wall in Indonesia, ...

Route 66 is lined with state and national parks where visitors can see petroglyphs, canyons, lakes, historic sites, and desert vistas.