Black Canyon of the Gunnison National Park in Colorado on the outskirts of the American Southwest is a gorgeous deep & dark canyon with breathtaking views of the Gunnison River below and the Rocky Mountains in the distance.
There are two sides, a north and a south rim and both have hikes & a fantastic scenic drive (14 miles one-way) with over 10 lookouts including the awe-inspiring Cedar Point that allows you the view of the Painted Wall with its veins of pink pegmatite that flow through the black gneiss.
There is also a campground and a nice visitor center. Just make sure you head there in the warmer months as the road can be closed with snow and ice.