10 Downing Street is the address of the British Prime Minister. Its nickname is number 10 and its black front door is famous all over the world ! The house is about 275 years old and it's in the centre of London , near Buckingham palace and the Houses of Parliament. Its a very big building. There are about 100 rooms.There's a private apartment on the base floor. The Prime Minister and his family live here.There's also a big kitchen in the basament. On the other floors there are offices and official rooms for the British Government. The house isn't open to visitors.