When we were in Paris last week, I wondered what’s behind the facades of the big buildings that line the boulevards. The reason I wondered is that most of the blocks of Paris are oblongs or triangles formed of large buildings, with no breaks for visible alleys. A triangle leaves a lot of space near the middle–in contrast, for example, to the narrow rectangular blocks of Manhattan. If you fill a triangle with buildings, no light will reach most of the interior–especially near the middle of each block, where the shape is widest.
Thanks to Google Earth, one can see what is going on from above. The picture to the left shows the block where my wife and I stayed last week. Like most of the blocks of the Right Bank, it is actually filled with trees. Paris is a much greener city than you can tell by walking its streets, but half of the green is private and hidden behind the lovely stone facades.