The first thing that one notices when arriving on the UK is that cars here go on the left side of the road.
This can be a traumatic and dangerous experience, because even after 6 months here, i still find myself sometimes looking at the wrong side before crossing.
But, when you ever ask a Britt why they drive on the wrong side, they will always correct you by saying they drive in fact on the right side... which is the left!
Confusing? Let me explain.
Until the 1700's every country was traveling on the left side. This was because times where of danger on the roads, and you would want to keep your sword arm between you and the possible assailant. Same thing for the knights. This was because most people where right-handed (either by birth or force of education).
Then comes Napoleon Bonaparte. He was left handed, and as a way for him to keep is sword on the outside, his army had to travel on his right. After that, all the "french world" was on the right. And when the USA also went right, this meant that the left side was doomed, even more with the rise of the automobile industry, that for a long time, only produced right sided vehicles.
So, crossing the streets in the UK is dangerous for foreigners.