In about 1968, my dad drove round the roundabout in front of Buckingham Palace so us kids could get a better gander at the palace.
We got pulled over by a Bobby on the third circuit, and I kid you not, his first question was 'What's going on here, then?'
We were told if we wanted a better look, we would have to park the car and walk - like everyone else.
The answer to the question is 3.
Funnily enough, the concept of a circular traffic junction - in a form similar to a roundabout today - was first introduced in Washington DC in the 1790s, including the Dupont Circle.
So literally speaking, you septics invented the roundabout traffic circle.