Grandparents will do a lot of things for their grandchildren. Tom and Alice Blair renovated a waterfront house on Maryland’s Eastern Shore for theirs.

“That’s why we built it, really,” Alice said. “It was going to be a family retreat, and it was the perfect family retreat.”

The Blairs didn’t know that they wanted to live on the water until they bought this property on the Miles River in Easton in 2002.

“We didn’t understand what we were missing,” Tom said. “It’s not a case of we never wanted to live on the water. We never understood what it was like to watch the bald eagles and the ospreys fly around this place.”

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When the Blairs bought the house, they knew it needed to be expanded to accommodate their 16 grandchildren. They hired G.L. Smith Associates to design the renovation and Visnic Homes to execute the design.

“The house had good bones,” Tom said. “We wanted to take something that was good and make it truly exceptional.”

Once the grandchildren started visiting, the Blairs made sure that they never lacked for things to do.

“One of the grandchildren said, ‘Grandma, I’d really like a horse,’ ” Alice said. “Well, in three weeks, we had a barn and a horse. It was one of those things that we spoiled them to death.”

The horse was joined by more horses, Herefords, goats, alpacas and chickens. For those less interested in farm life, there is a swimming pool and a dock for boats and personal watercraft.

Not everything was for the grandchildren. A grassy airstrip was added, near where the goats grazed, for Tom to land his vintage World War II planes. He designed the library to accommodate a British Spitfire that hangs from the ceiling. And a fondness for church ruins led to the property’s most evocative feature — ivy-covered stones arranged to resemble a tumbled down place of worship. The serene spot has been the site of a family wedding and christening.

The layout of the 16,774-square-foot main house allows for large gatherings as well as intimate conversations. There are formal living and dining rooms but also relaxed family and kid spaces.

“It was a wonderful place where Tom and I felt cozy, but I also felt cozy with 20 people in it,” Alice said. “It’s an unusual house that way.”

Many rooms have floor-to-ceiling windows offering panoramic views of the water and the spectacular sunsets.

For the Blairs, this property has been an oasis where they enjoyed spending time with their grandchildren.

“But they’re all grown up now,” Alice said. “Most of them are in college or out of college. Times change.”

In addition to a six-bedroom, nine-bathroom main house, the 36-acre property includes a three-bedroom guesthouse, a two-bedroom farmhouse, a one-bedroom caretaker’s cottage, a greenhouse, two barns, multiple paddocks and several outbuildings that include a hangar for a plane. It is listed at $15.5 million.

Listing agents: Lori Leasure, Marc Bertinelli and Doc Keane, Washington Fine Properties