Lakota warrior Crazy Horse has long been a controversial figure, so perhaps it's apropos that his memorial follow suit.

Though he is best known for fighting against George Armstrong Custer at the Battle of the Little Big Horn, Crazy Horse led his tribe numerous times against settlers and miners in the Dakotas, Montana and Wyoming and elsewhere before his 1877 death at Nebraska's Fort Robinson. But forget his disputed role in the Battle of the Little Bighorn or the claims that he's never been photographed or the conflicting tales of how he met his end -- the real mystery is more contemporary: When is the sculpture in his honor going to be complete?

In the mountains of Black Hills, South Dakota, rests the Crazy Horse Memorial. It pays tribute to the Native American war hero with a sculpture that, at many times the size of nearby Mount Rushmore, will one day constitute the world's largest mountain carving.

That is, if it ever gets completed.

Though the project has been ongoing since 1948, it's far from finished, and there isn't a rush because ... well, there isn't a deadline.

"The organization is not trying to be difficult or using delaying tactics," said Patrick Dobbs, spokesman for the Crazy Horse Memorial. "There are project unknowns and circumstances beyond control that influence the work."

He lists harsh weather -- including lightning storms and blizzards -- and the mountain's high iron content, which makes the rock tougher to carve, as factors that have put a halt on the sculpting progress.

That's not to mention that the sculpture will stand 563 feet tall, a few feet higher than the Washington Monument.

Creator shuns assistance

Another factor is funding. According to Dobbs, the Crazy Horse sculpture is a nonprofit project and is funded entirely by admission fees and donations.

"There were offers by elected government officials and high-ranking department appointees to seek funding as amendments to bills for other federal legislation," said Dobbs. "However, (Polish sculptor) Korczak Ziolkowski turned them down. He did not believe the government would complete the carving."

Ziolkowski saw the American government as flaky when it came to making agreements, Dobbs said, adding Ziolkowski was dismayed by the 1868 Fort Laramie treaty, which handed the Black Hills over to the Lakota but required their children have an "English education" and failed to address gold rights, resulting in years of conflict.

The government seized the Black Hills nine years later, and the ensuing court battles continued for more than a century.

Dobbs said Ziolkowski was also troubled by Mount Rushmore sculptor Gutzon Borglum's struggle with federal officials over funding and control of the American landmark.

Despite these factors that prompted Ziolkowski to spurn government assistance, it should be noted that Rushmore was completed after only 14 years.

The New York Times reported in May that admission fees totaled $3.8 million in 2010, and the memorial received more than $19 million in donations over the last five years.

Some Native Americans, including descendants of Crazy Horse, think with numbers like that the monument should already be finished.

Seth Big Crow, whose great-grandmother was Crazy Horse's aunt, has mixed feelings about the memorial. In an interview with Voice of America, he said the monument could serve future generations and may be the American equivalent to the Easter Island monoliths.

"Maybe 300 or 400 years from now, everything will be gone, we'll all be gone, and they'll be the four faces in the Black Hills and the statue there symbolizing the Native Americans who were here at one time," Big Crow said.

The Eastern Island monoliths have long been considered one of the world's great mysteries. Ancient Polynesian settlers to the island built the giant volcanic-stone figures, and while they are thought to pay homage to deities or ancestors, no one knows exactly what they represent.

The sculpture of a lifetime

Ziolkowski began carving the Crazy Horse monument seven years after the completion of Rushmore.

Chief Henry Standing Bear, then-leader of the Lakota tribe, didn't like the four huge American faces peering over his people's land, so he asked Ziolkowski if he could carve a monument in honor of a Native American legend.

"My fellow chiefs and I would like the white man to know the red man has great heroes also," Standing Bear wrote in a 1939 letter to Ziolkowski.

Ziolkowski worked on the carving until his death in 1982 at age 74. His dying wish was for his wife Ruth, now 86, and their 10 children to finish the sculpture. Ruth is president and CEO of the Crazy Horse Memorial Foundation, and seven of the children are working on it to this day.