A snatched glimpse through the railings at the end of the street is as much as you're likely to see these days of the country's most powerful address — No. 10 Downing Street, home of whoever happens to be the current prime minister. The second-most powerful person in the land, the Chancellor of the Exchequer (the finance minister), lives next door at No. 11. There's a connecting door between the two to spare the great officeholders the indignity of having to walk outside whenever they want to talk.

It is not a grand place, certainly not when compared to some of the extravagant residences enjoyed by other heads of state, such as the U.S. White House or France's Elysée Palace. But then, unlike those buildings, it was never designed to be a center of political power, just a simple house on a regular residential street named after the man who built it, George Downing. Its elevation to greatness came about entirely by accident when the country's first prime minister, Robert Walpole, moved here in the early 18th century, once the previous tenant, a Mr. Chicken, had moved out. A precedent had been set and Britain, being a country that likes to make up traditions and norms as it goes along — this is a country, remember, with no written constitution — decided to stick with it. Every prime minister since has followed in Walpole's footsteps, for no other reason than that it seemed the thing to do.

Visitors may not enter or approach the house, which is partly visible through a guarded gate on Whitehall.