Had they known, perhaps the 23-room house, which dates back to 1797, would have then been included on their trip.
If the newlyweds ever do come for a tour, there's a good chance "Pops" will be their guide.
Jack "Pops" Norris, 75, specializes in tours for children.
The animated guide goes to great lengths to make history come alive and interesting, and one of his many props is a picture of the royal couple.
"Kate Middleton is the 13th cousin of Francis Scott Key," Norris told a group of youngsters, ranging in age from 4 to 12, during a recent Wednesday morning tour.
After singing a verse of the "Star-Spangled Banner" on the second floor of the historic house, he added, "Former Gov. Bob Ehrlich spoke from this balcony, too."
Norris leads the "At Union Mills With Pops" tours at 11 a.m. and 1 p.m. each Wednesday at Union Mills, located on Littlestown Pike, north of Westminster. This is the second year Norris has hosted the Pops tours, and he couldn't be more proud.
Prior to the child-oriented tours, "we were taking young people through here, and it was totally boring," said Norris, a longtime volunteer at Union Mills.
He said that he was inspired by a teacher who took his class through the historic homestead in a way that caught Norris' eye.
"He made it so interesting for the students," Norris remembered.
It gave him the idea to do the same — enliven the tour with fun, songs and the "pops" persona.
"I had taught 17 years of Sunday school and was Santa Claus for 20 years. I put it all together," he said.
"The idea," Norris said, "is (that) history is fun."
As he gathered his group into the living room of the Shriver house on a recent Wednesday in July, Norris informed them that anyone caught yawning would hear his whistle blow. Before the 45-minute tour was through, the shrill sound of the whistle would fill the air several times — much to the delight and surprise of the participants.
"He (Norris) is very knowledgeable. He loves the homestead, and it shows," said Jane Sewell, executive director of Union Mills. "The idea of the tours is to get kids excited, and it's working."
Union Mills Homestead was originally built as two log cabins. As it expanded over the years, the house served many purposes, acting at times as a post office, schoolhouse and inn.
When the home was left in the care of the county, it contained all its original artifacts and furnishings from the Shriver family, according to Coral Collins, tour coordinator.
"It's a very unusual museum," Collins said.