WASHINGTON -- Prince Charles and his wife, Camilla, got the royal tour of the U.S. capital on Wednesday, being ushered around Washington's monuments and memorials on the National Mall by a handful of American luminaries.

The British royal couple was joined by two civil rights leaders for their tour of the Martin Luther King Jr. memorial -- the Rev. Jesse Jackson, a protege of King; and Rep. John Lewis, who marched in the "Bloody Sunday" demonstrations for minority voting rights 50 years ago.

Charles and Camilla spent about 20 minutes touring the King memorial. The couple paused briefly to read some of King's quotations about the civil rights movement that are engraved in stone.

"Darkness cannot drive out darkness, only light can do that. Hate cannot drive out hate, only love can do that," read one quotation where the royal couple paused to see King's words from 1963.

Harry Johnson, the president of the foundation that built the King memorial, said he gave the royal couple a stone from the memorial's granite as a gift.

The royal couple also visited the Lincoln Memorial, where they were greeted by historians Michael Beschloss and the Pulitzer Prize-winning Doris Kearns Goodwin, author of "Team of Rivals: The Political Genius of Abraham Lincoln."

At George Washington's Mount Vernon estate, Charles and Camilla toured the iconic mansion overlooking the Potomac, stopping outside on the veranda to appreciate the view.

Charles later toured the working farm on the estate, viewing a demonstration of a specially designed threshing barn by Washington and patting the horn of an ox named Jed.

"You've got to watch these," Charles quipped, referring to the horns.

Kitty Morgan of Mount Vernon brought her two sons to the estate and was one of hundreds who lined up to catch a glimpse of the couple. The boys were rewarded with the chance to shake Camilla's hand.

Originally from Britain, Morgan said she "decided my boys, being British, needed to see their future sovereign."

She said they never would have been able to get so close to the royal couple in England because the crowds would have been overwhelming.

The couple is also visiting the National Archives, which holds the U.S. Constitution, the Declaration of Independence and a copy of the English Magna Carta.