No public roads lead to this section of the river. The best way to see the white cliffs is on a leisurely float trip in a kayak, canoe or raft, camping along the way. It is also possible to book a one-day guided trip via small motorboat (power boats are strictly regulated in the Monument, which helps maintain the sense of wilderness). Headquarters and an excellent visitor center for Missouri Breaks National Monument is in the historic town of Fort Benton, Montana.
More information on Upper Missouri Breaks National Monument: http://www.blm.gov/pgdata/content/mt/en/fo/umrbnm.html
Eroded cliffs of white sandstone make for some dramatic scenery where the Missouri River flows through central Montana at the Missouri Breaks National Monument. Most of this remote country looks the same as it did when Lewis & Clark led the Corps of Discovery through this territory, and it's possible to pick out some of the landmarks and their campsites as described in their journals. This stretch of the Missouri is also officially designated as a Wild & Scenic River.