Number 10 Downing Street has opened its famous front door to the public after more than 270 years, with a virtual tour for web users.
Visitors can look around the Cabinet Room
Visitors can look at rooms, find out historical information and click on objects such as paintings and furniture for extra details.
Tony Blair told the BBC the tour was "an excellent way of showing the tremendous history of this building".
Number 10 has been used as a home by prime ministers since the 1730s.
Clocks, chairs and paintings
Mr Blair said: "I feel very lucky to live and work here and if we can share just a fraction of the fascination of this extraordinary place, then the tour will enthral a great many people online."
Visitors can scroll around eight parts of the house, including the Cabinet Room, entrance hall and Grand Staircase.
The site allows the public to look at the art on display at No 10
They can also click on objects such as a portrait of former prime minister Sir Winston Churchill, antique clocks and chairs, each of which gives a description and historical information.
The tour's developer, Aral Balkan, said: "I thought it was too interesting a project to pass up. Working on it has been very exciting and a great privilege.
"Downing Street is an extraordinary place and I hope to have captured a real sense of the history and importance that comes from going behind that door."
King George II gave the house to the then Prime Minister Robert Walpole, who lived in the building from 1735.
Earlier this year, visitors to the Number 10 website were asked to send in their own "e-petitions".