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.
"Most houses have ropes, and you can't go into rooms. Here, you can go into rooms. Everything is the real thing."
Norris points out various items to his group, including an organ grinder, complete with a stuffed monkey; a butter churn; and several antique toys.
All the while, he compares them to today's conveniences — the wind-up record player compared to today's iPod; the bricks used to warm beds at night compared to a heating blanket.
"What you want in 45 minutes is 214 years of history," Norris said of the tour content.
"(The children) are not going to remember everything," he said. "Sometimes, they start laughing so much we can't even do the tour."
Included in the tours are visits to the gristmill, a working mill where one can assist with grinding whole wheat, buckwheat and cornmeal; and then sample cookies made from the goods.
A small gift shop is also on the property, as are a blacksmith shop and a tannery building.
Upon learning how sausage was made with scraps of meat pushed through an animal's intestine, William Jordan, 7, made a declaration to his grandmother, Janet Long, after the tour.
"NO sausage," William said.
Laughing, Long said they both enjoyed Pops' history.
"He did a great job with them, especially with the ages he had," Long said. "He was amazing."
Though they live only a few miles away, it was the Peacock family's first visit to the homestead. They enjoyed it.
"I loved it," said Corinne, 9. "How they make the toys was really interesting."
"My only desire at this point is seeing those kids laugh," Norris said between tours. "I enjoy it."
At Union Mills With Pops tours continue Wednesdays, at 11 a.m. and 1 p.m. through August at Union Mills Homestead, 3311 Littlestown Pike (Route 97), Union Mills. Call 410-848-2288.