Black Canyon of the Gunnison (River) National Park is just a few miles east of Montrose, CO. The south rim entrance and visitor center is accessible from either Montrose or Gunnison, CO via highway 50. The north rim entrance and visitor is accessible from Delta, CO via highway 92 (and is a long drive just to get there). Both rims have a camping area.
The canyons are very narrow because the Gunnison River itself is very narrow. The reason the area is called Black Canyon is because the sunlight rarely reaches the canyon walls because they are so tall and so close together.
This park is very impressive even though it is not well known around the country. From the south rim there is a 22-mile winding road with 11 stopping points along the way. At most of them, you park your car and hike some distance to the rim of the canyon. You will never be disappointed once you get there. Most of the stopping points have a variety of paths to take.
My personal favorite spot was Cross Fizzure Views. It offered a large rim area with dozens of paths. I found a secluded spot and sat in complete silence for half an hour. I even returned to the stopping point on the way back down from the end point.
Cedar Point was also a good stopping place. It had a huge horseshoe-shaped rim to walk around. It presented several "dangers" however. I lightly sprained an ankle twice on rocks. While climbing up rocks on the far side of the rim I did not see a tree limb. It caught me right in the middle of the forehead. Nice big scrape with a headache to match. Then, while climbing down, I put my hand down for balance and found a plant with a bunch of prickly burrs, some rather large. Ouch!
High Point was the end of the trail. It was the highest point and had restrooms. It had a trail over 1,300 yards long leading out to the furthest reachable point in the park's south rim. Incredible view that went for miles. One local lady brings her dog up there each morning to walk.