Petra Stanev attributes some of that closeness to the fact that the family left Bulgaria when she was a child, and that, for a while, they had only one another for companionship.
Todor Stanev is an astrophysicist; Kralevska, a printmaker. He is a professor at the University of Delaware, and for more than 20 years the couple's full-time home has been in Newark, Del.
But Petra, her husband and their two children live in Philadelphia, Kralevska said, and she and her husband want to be closer.
"We want to see our grandchildren more frequently and, when we retire, it would be nice to be close to the Art Museum and to be able to go to the theater and other things here," Kralevska said.
"I showed her the apartment because a friend of mine lived in the building and told me about the vacancy," Petra Stanev said. "I thought we were just beginning to look, but my mother decided right away that they would take it - that's the way she makes decisions."
What her parents bought was a 1,000-square-foot condominium in which the previous owners lived for many years, but without doing much work.
"The bedroom took up half the apartment, and a wall separated it from the best view in the house - my parents love good views. There were too many closets and a large kitchen with an eating area that was walled off," she said.
Now that the condo has been redesigned, it seems larger, and Todor Stanev has a great view from his desk that looks northwest toward the Parkway and the Art Museum's Perelman Building.
"It is important to my father to be able to see trees, and this is the only really good view in the apartment," Petra said of the corner where the desk is located.
Another benefit: Removing the wall also opened the bedroom to light from the window.
"The other windows just show a view of other apartments," Petra Stanev said. "It is unusual, but we actually wanted to cut out extra closets; there were two that weren't needed."
Created in the redesign was an open, curved kitchen whose stainless-steel finishes contrasted nicely with a bowl of oranges on the counter during a recent visit.
"We didn't need a kitchen table - we can eat at the dining room table," Kralevska said.
A tiny, 1960s-style bathroom was outfitted with colorful tile walls and a sink that sits on a gleaming wood base.
Cork was used on the floors, to help with soundproofing.
"They like modern furniture, mid-20th-century modern, and this floor without carpets shows it off," Petra Stanev said.
In the transformed space, the couple's own designs stand out, as well. Lighting the entrance hall is a chandelier, crafted by Kralevska, from empty seltzer bottles that looks as if it had been made instead from crystal.
And on a wall in the dining area are artworks Todor Stanev fashioned from paper, wrappings, and match covers that depict pine, gum and apple trees.
"Yes, we always like to take found objects and make them into something," Kralevska said.
The couple's daughter/architect said it was fun helping create their unique apartment.
Though she likes to think she and her husband are sensitive to all their clients, Petra Stanev said, working with her parents was "something special."