Downing Street is the street in London, England, United Kingdom, which for over two hundred years has contained the official residences of two of the most senior British cabinet ministers: the First Lord of the Treasury, an office held by the Prime Minister of the United Kingdom, and the Second Lord of the Treasury, an office held by the Chancellor of the Exchequer. The most famous address in Downing Street is 10 Downing Street, the official residence of the First Lord of the Treasury—and thus, in modern times, the residence of the Prime Minister. Number 11 is likewise a term for the Chancellor of the Exchequer or his or her office. - Source: Wikipedia
