Speaking of European countries and size/distance, according to google maps it takes almost an hour less time to drive between London and Paris as it does to drive between San Francisco and LA.
If anything, I expected the difference to be larger: London is in the far south of Britain and Paris is in the far north of France, so they are quite close together, whereas SF and LA are pretty much at opposite ends of California. (OTOH, I had no clear idea how long it'd take to take the train in the tunnel below the Channel -- according to Google Maps it takes one hour and a half to drive from Dover to Calais.)
(Exercise for the reader: guess how long it takes to drive from Milan to Rome and how that compares to those two.)
There's a lot of background mess in our mental pictures of the world. We try and be accurate on important issues, but a whole lot of the less important stuff we pick up from the media, the movies, and random impressions. And once these impressions are in our mental pictures, they just don't go away - until we find a fact that causes us to say "huh", and reassess.
Here are three facts that have caused that "huh" in me, recently, and completely rearranged minor parts of my mental map. I'm sharing them here, because that experience is a valuable one.