66 years ago Friday sculptor Korczak Ziolkowski accepted the invitation from Lakota leaders to begin work on Crazy Horse.
Two blasts at the memorial marked the anniversary.
The blasts removed about 880 tons of rock near the horse's head.
Jeff Hermanson, a mountain carver at the monument, said each year they celebrate today with a blast to honor Ziolkowski's dream.
"It's the anniversary of Korczak's first trip out to the Black Hills. And really when the whole dream started and so we celebrate that. And maybe that's why we had two blasts today to make it a little extra special," said Hermanson.
The blast also marks the 30th anniversary observance of "Korczak Ziolkowski Day in South Dakota."