Background of arrondissements

Before getting into each of the arrondissements (arrs) I'll tell you a little bit about what they are.  We don't really have the equivalent of arrs in the US; virtually every medium-small town to big city in France is split into districts - the arrs - for administrative purposes.  Their being official is rather modern, but more often than not the arrs are based on long-standing historical borders.

There are twenty arrs in Paris proper and one interesting thing about them is that they are numbered roughly according to when they were incorporated into the city.  So the 1st arr is considered the very oldest area of Paris (although really the 4th and 5th probably are, as they date back to Roman times, but the 1st was the first area of the "French" city), going on until the higher teens, which were considered suburbs only a century ago.

However, their numbering also follows a "snail shell" pattern starting from the first: they make a tight circle around the center of the river, then a wider circle.

In this map you can see how they start from the 1st, which is just on the north side of the river [we consider this the "right bank," and the south side is the "left bank"], and form the snail pattern.  It also shows the more common names of most of the arrs.

When you meet another person who lives or has lived in Paris, the first thing you ask is what arr they were/are in.  Each arr has a distinct history and current atmosphere, different things they are known for.  Usually when you're planning a meet-up with people you'll give them a general idea of what type of place you're going just by saying which arr it is in.

I hope the posts about them are interesting, and please let me know if you'd like me to continue them after I post the first one!