No. 11, home of the Chancellor of the Exchequer and No. 12, home of the government's chief whip, are all that remains of the original 17th century terrace. The other buildings on the street date from 1868 and these interconnecting houses have been modernized over the years to accommodate the many required offices, as well as to provide a flat on an upper floor for the Prime Minister's family.
At the end of Downing Street today, are a pair of iron gates, along with security guards, to prevent public access to the cul-de-sac.