Downing Street is home to two of Britain's most senior Cabinet positions, the Prime Minister (in his capacity as First Lord of the Treasury) who lives at Number 10 Downing Street and the Chancellor of the Exchequer (in his capacity as Second Lord of the Treasury) who lives at Number 11 Downing Street.
Downing Street is in Whitehall, the area on the edge of the grounds of Buckingham Palace running north from Parliament Square towards Trafalgar Square.
Since 1989 Downing Street has been blocked off by steel gates to protect the Prime Minister from "terrorist attacks".