The Billings Rimrocks(The Rims), the often neglected and unjustly overlooked climbing mecca of eastern Montana. The most popular climbing area is above the Gregory subdivision. There are some great cracks and some great although sometimes fragile face climbs. Toproping is the norm because of the aforementioned rock quality although cracks usually take good medium to large sized pro. There are a few bolted routes but choose your poison as sandy and brittle rock, junk hardware and poor bolting abounds. Most routes have easily accessable "bolt"(epoxied carriage bolts threaded through small diameter chain links, check and back them up) or natural anchors. A great local winter climbing destination but avoid it during the heat of the summer after 10:00am. Also be aware of the extreme rockfall potential and belay and hang out well away from the base of the climbs(helmets advised). Don't forget to bring your sense of humor and as always pack out all trash including cigarette butts, tape and anything else you're tempted to leave behind.
Mountain Project's determination of some of the classic, most popular, highest rated routes for Billings Rimrocks:
Park here for Gregory 45.802335,-108.586486 If you don't have a GPS print up a google map to that location. Hike up an obvious trail, staying on the right fork for the first few feet, away from the Heavy Poison Ivy growth at the base of the boulder. hike up and left (west) to get to the "walkup" area (easiest lead up) at 45.803643,-108.589483 the climbs are both left (west) & right(east) of here. You can also buy a guidebook (Super Sand Land, Joel Anderson) at Steep World.
This video is well worth the watch and will give you the true flavor of climbing in Billings.
Yes, and thanks MTKirk. The guidebook "Super Sand Land" is available at Steepworld and The Basecamp. Any edits, major news, and new route info will be posted to the book's corresponding website. billingsclimbingguide.blogspot.com/