Later Friday, the king and queen visited the American Swedish Historical Museum on Pattison Avenue as well as the Barnes Foundation. On Saturday, they are scheduled to attend events in Chester; New Castle, Del.; and Wilmington.
"This is an amazing moment in my life," gushed Henry Bernstein, 11, a fifth grader from Chevy Chase (Md.) Elementary School as he stood with his class outside Independence Hall awaiting a glimpse of the royal couple.
"To see the king and queen of Sweden - this is going to be a memory."
Henry's teachers and chaperones laughed, expressing puzzlement at his enthusiasm for the royals, who appeared to be quite nice but aren't exactly household names here.
Much about Sweden - the size of California but much quieter - isn't known in America, beyond Ikea, the pop group Abba, and The Girl With the Dragon Tattoo.
Around 50 people cheered the royal couple as they exited Independence Hall, many of them admitting afterward that they had no idea who the poised and handsome duo was. But it was a warm day and they already had their cameras out, so -.
Earlier in the afternoon, the king and queen visited the Liberty Bell and were honored by Mayor Nutter in City Hall.
There, they exchanged gifts - flowers and a Waterford plate etched with Philadelphia landmarks for the royals; an autographed photo of the couple for the mayor.
Nutter, demonstrating some European flair, kissed Queen Silvia lightly on both cheeks. She beamed.
"It's wonderful to be back," Carl Gustaf told a gathering of city officials and guests, smooth as a touring singer revisiting an old venue.
The king has been in the area several times before, including in 1976 in Swedesboro, 25 miles south. The town is believed to have been settled by Swedes around the time New Sweden was established.
Things were not so cheery in Swedesboro on Friday. Mayor Tom Fromm said that a member of the local historical society had lobbied for a royal return visit, to no avail.
"We were really hoping they'd come, but -," Fromm said glumly.
For a people who never wanted a king, Americans certainly make a fuss about royalty.
The constant mania around Catherine, Duchess of Cambridge, and her husband, Prince William, as they await a baby shows that we have quite an appetite for the lives of blue bloods.
It's the same in Sweden, said Swedish freelance reporter Linda Forsell, who lives in New York and covers American culture.
"People in Sweden watch the royals like they watch TV," Forsell said. "They may not be as famous as the British royals in America, but they're huge in Sweden."
Silvia is celebrated for her work with the World Childhood Foundation, which she founded to help abused children, said Tracey Rae Beck, executive director of the American Swedish Historical Museum.
The king is interested in environmentalism and is an avid supporter of scouting, she added.
The two have a daughter living in New York who will marry an American in Stockholm next month.
Will Americans be glued to coverage of that royal wedding? Maybe not, but the Swedes will.
"People love royals because they live a life others can't," Forsell said. "They live lives we only dream of."
Contact Alfred Lubrano at 215-854-4969 or firstname.lastname@example.org.