I'm sorry, both Google and silly French Wiki got it wrong, and I yet pasted their mistake on here like a dummy while I knew it was wrong, confused and stuck in a
what the heck? when I saw the distances they reported.
Of course Massy's never been 25km away from Central Paris. It's actually twice closer to it. You just don't get that 10-storey average contemporary density 25km away from the central city, which is normal. I was thinking the correction was a little necessary to the thread, cause I wouldn't like the dense urban area to sprawl too much at all.
Sometimes when you're just 30 miles away from Paris, you get a feeling that you're lost in a deep countryside with some farming fields around and small villages here and there. That's kinda fun from time to time and definitely necessary to the region. May be useful to repeat this informative here...
Here's a comprehensive map of entire Île-de-France (often nicknamed the Paris region) if you're curious, showing all towns encompassed within its administrative limits. There's a lot of them local municipalities. This is still the very land of the Gallic villages and small towns with their too many little chieftains.
http://www.cartograf.fr/regions/ile-..._detaillee.gif
Obviously, this is way larger than the actual urban area; not all of this is urbanized, far from there. I would call most the regional area semi-rural. Generally speaking, the farther away you get from Paris, the more rural it tends to be. However, some sort of urbanization stretches along the Seine, Oise and Marne rivers, up to Mantes-la-Jolie and around Pontoise to the West, Meaux to the East and Melun to the South. Versailles and its surroundings are more dense than the average, too.
The most convenient in that matter is yet to take a quick look at a density map.
This was in 2007 and most likely didn't change much since then.
http://www.slate.fr/sites/default/fi...op2007_IDF.jpg
Looking at both those maps, you see that historically, local urban sprawl roughly followed the rivers that once were extensively used for freight. They still are to some extent, as you still pass a bunch of freight barges on the Seine, but of course highways and railways widely relieved them.