Number 10 Downing Street has been the official residence of the British Prime Minister since King George II presented it to the First Lord of the Treasury, Sir Robert Walpole, and he took up residence there on 22 September 1735. The brass sign on the door still says, "First Lord of the Treasury."
The world's most famous street, Downing Street, is named after Sir George Downing who was born in Dublin, Ireland, but spent his early days in Massachussets, New England - now the United States. He was one of the nine graduates of the first graduating class of Harvard College in 1642. A few years later he came to England and in 1657 became the British Ambassador to The Hague. In 1682, he built 15 to 20 townhouses in a cul-de-sac that is now called Downing Street. The houses he built were cheap and poorly built. The current number 10 was actually No.5 and was renumbered in 1779.
Sir Winston Churchill, British Prime Minister from 1940-45, wrote about Number 10: "Shaky and lightly built by the profiteering contractor whose name they bear."
The prime minister’s home is on the third floor, with offices occupying the other two floors. Number 10 Downing Street has become a symbol of England on par with Westminster Abbey and Buckingham Palace. There’s not much for tourists at 10 Downing Street – it’s gated off and there are no tours. It is an interesting photo op, and just a couple of blocks from Westminster Palace, so it wouldn’t hurt to pop over while in the neighborhood.
Closest tube station: Westminster