Why does the color change on the outside of the monument?
When the monument was under construction the project ran out of money. It sat uncompleted for 27 years until they could restart the project the stone above the line wasn't exposed to 27 years of pollution and wind driving dirt/dust.
Did You Know?
Prince William Forest Park preserves the largest inventory of Civilian Conservation Corps structures (153) in the National Park System. Four of the five cabin camps are listed on the National Register of Historic Places as historic districts.