Michelle Obama's speech Monday at the Democratic National Convention electrified the crowd gathered in Philadelphia, quieting the boos from supporters of Sen. Bernie Sanders and leading to rousing cheers.

She used her personal experience as first lady to emphasize the strides the United States has made since it was founded and aimed squarely at Republican presidential nominee Donald Trump's promise to "make America great again."

"I wake up every morning in a house that was built by slaves," she said. "I watch my daughters, two beautiful, intelligent, black young women, playing with their dogs on the White House lawn. And because of Hillary Clinton, my daughters and all our sons and daughters now take for granted that a woman can be president of the United States.

"So, look, so don't let anyone ever tell you that this country isn't great, that somehow we need to make it great again. Because this right now is the greatest country on earth."

The bold statement left some people wondering: Was the White House really built by slaves?

Yes, it was.

According to the White House Historical Association, a private nonprofit founded by first lady Jacqueline Kennedy, commissioners in Washington, D.C., were tasked with building the capitol in 1792 under direction of the president. Land was set aside by Virginia and Maryland – both slave states – and commissioners planned to use European laborers as builders.

Recruitment floundered and commissioners turned to both enslaved and free African-Americans. They provided "a bulk of the labor that built the White House, the United States Capitol and other early government buildings," according to the White House Historical Association.

Slaves were trained at the government's quarry in Aquia, Virginia.

"Enslaved people quarried and cut the rough stone that was later dressed and laid by Scottish masons to erect the walls of the president's house," the association said.

Immigrants from multiple European countries also helped build the White House.

Monday wasn't the first time that Obama has made such a statement. During a commencement speech in June for the City College of New York, she said, in part:

"Graduates, it's the story that I witness every single day when I wake up in a house that was built by slaves, and I watch my daughters – two beautiful, black young women – head off to school, waving goodbye to their father, the president of the United States, the son of a man from Kenya who came here to American for the same reasons as many of you: to get an education and improve his prospects in life."