Though Kensington Palace may look more like a series of townhouse apartments than a palace, it was perhaps Diana's one safe haven: the place where she lived and raised her children.
And it is here that William and Kate will raise theirs. Diana paved the way for a new kind of royal parenting, setting a standard for mothering a future monarch.
Prince William has said he wants to spare his wife the inevitable comparisons to his mother. But in many ways, Diana has been part of this pregnancy from the very beginning.
The world waited two years for Duchess Kate's announcement, but Diana was pregnant just three months after her wedding. From the beginning, she rebelled against the royal traditions of arm's-length parenting.
Prince William was the first heir to the throne to be born outside palace walls, in a hospital. This was followed closely by another royal first.
"Diana is largely reported to be the very first mother within the royal family to breastfeed," said ABC News royal correspondent Victoria Arbiter. "Of course, that's hard for us to know for certain, but Queen Victoria was adamant that she found breastfeeding disgusting. She thought babies were ugly, and she didn't really enjoy any part of being pregnant, yet she had nine children."
Because of Diana, that taboo has been removed for Kate and the new baby.
"I'm sure she'll do exactly what most women in this country do," said Daisy Goodwin, author of "My Last Duchess." "Which is to breastfeed for two or three months. And then, you know, get some stuff and give them a bottle."
Princess Diana broke with the royal tradition of spending months touring the Commonwealth without the kids. She insisted on including nine-month-old William on an official visit to Australia.
"And [people] were like, 'Breaking royal precedent,'" Goodwin said. "But it was brilliant, because ... we all really warmed to her. Because no woman wants to leave her baby, and that was what made Diana so lovable -- that she always absolutely adored her children."
Judy Wade, royal contributor to Hello! magazine, said she used to call Diana a "rebel royal mum" because of Diana's breaks with tradition.
"Sources within Kensington Palace would say to me, 'Every morning the boys would run in their pajamas into her bedroom, and she'd have her arms open wide to hug them.'"
At Diana's insistence, William became the first heir to the throne to attend public school. His personal bodyguard, Ken Wharfe, was with him on his first day.
"Diana said to him in the car, 'Now listen, William, there's going to be a lot of photographers at your new school, so you need to behave yourself.' And he, in this sort of just William way, said to his mother, just below the pink cap, 'I don't like 'tographers,'" Wharfe said.
"She said, 'Well, you're going to get this for the rest of your life,'" Wharfe said.
Arthur Edwards, royal photographer, has been photographing William since he was born.
"William hated the press," Edwards said. "He didn't like the whole idea of being photographed all the time. He just didn't accept it."
Still, Princess Diana wanted to give her sons a normal life.
For centuries, young royals grew up separately from their subjects. When Queen Elizabeth II was young, Arbiter said, the palace had to bring a Girl Guide company into Buckingham Palace so that she had children her own age to socialize with.