The most unusual of Billings’s Rimrock attractions is the Pictograph Cave State Monument (406/247-2940, 8 a.m.–8 p.m. daily May–Sept., $5 per vehicle for non–Montana residents). Located southeast of Billings on the south side of the Yellowstone, the caves were inhabited for about 10,000 years. A succession of cultures has lived here, beginning with a tribe of prehistoric hunters.

Excavations have yielded almost 30,000 cultural artifacts of early Paleo-Indians, making this one of the richest archaeological sites in Montana.

The road into the monument passes by spectacular cliffs and ponderosa pine forests. At the site, three caves have been cut into the sandstone by water erosion.

The best-preserved cave paintings are in Pictograph Cave. Here, buffalo, elk, prehistoric animals, and figurative and abstract designs are just visible on the sandstone walls of the cave. That the paintings have survived at all is amazing, especially after repeated assaults by vandals with spray paint. However, nature eventually washed off the spray paint, and the colors of the painting, made from plant resins, cherry juice, animal fat, charcoal, and soil, once again show through.

The other two caves, Ghost Cave and Middle Cave, were also inhabited by prehistoric Indians.

A hard-surface 1,000-foot trail links all of the caves from a central parking lot. A very nice picnic area (but no camping sites), water, and toilets make this a great place to stop and explore. The abundance of birdlife along the rims and the presence of typical prairie flora make the monument grounds a mini nature hike.

To find Pictograph Cave State Monument, take exit 452 from I-90 and follow the signs south along Coburn Road for five miles.