The royal residence of the late Diana, princess of Wales, opened to the public on Monday after an overhaul that cost 12 million pounds (about $19 million).

Kensington Palace, in the centre of London and next to historic Hyde Park, used to be the home of the princess of Wales, and is now the London home of her son Prince William and his new wife Catherine, duchess of Cambridge.

The palace became the focus of worldwide media attention on the death of Diana in a car crash in Paris in the summer of 1997, following which thousands of mourners placed flowers outside the metal gates of its main entrance.

"If you were to come past Kensington Palace last year, you would have thought 'that is a secret place, I can't go in there'," said Lucy Worsley, chief curator at the Historic Royal Palaces charity, which carried out the revamp and runs the area open to the public.

"But you can, and what we decided to do was to build a new entrance and four new exhibitions inside that sum up the past four centuries of the royal family," she added, saying Diana was "perhaps the most famous resident of the palace".

During the 19th century, the palace was the childhood home of Queen Victoria, Worsley told Xinhua.

"We see her whole life story laid out in the rooms where she lived," she said.

There are grand Georgian interiors from the 18th century, and the story of the palace's first royal residents began in the 17th century, she added.

The palace has been a home to royalty since it was bought by King of England and Scotland William III and his wife Mary II in 1689.

Christopher Wren, the architect of St Paul's Cathedral and many churches in the city of London, was commissioned to enlarge the palace.

One monarch, Mary II, actually died there, and visitors can see the room in which she died in 1694.

"Kensington Palace is split into two halves. There is the public half where visitors can come and there is the private half which still belongs to the royal family, which is not open to the public," said Worsley.

The project was a big one and took five years to complete, and it even had to get support from the local municipal planning authority.

"It began five years ago, with the starting point that this palace was hidden away from the public and from the neighboring Kensington Gardens," said Jo Thwaites, manager of the project.

Money came from donations, the Historic Royal Palaces charity's own funds and a national
lottery fund, Thwaites added.

"Historic Royal Palaces manages five royal palaces, and this one in many was the most
secret one and the least visited. Our goal was to increase the number of visitors and reconnect the palace to the park," said the manager.

About one million pounds were spent on re-landscaping a new garden, said Thwaites, adding that other big investments included a restoration for the interior and a new extension to the palace including shops, cafe and other facilities.

"It was all done in the traditional classical style, and there is also a new entrance loggia to celebrate Queen Elizabeth II's Diamond Jubilee, which is this year," said Thwaites.

The first visitor was the Queen, and "she liked it", said Thwaites.