In London you have the underground and in Paris the Metro, in every big city there is a train system and Chicago's is known as the "L"! Part of it is underground, but the majority of it is above ground hence it being known as the L, which is short for elevated. To be honest compared to other cities it is not very efficient, but it is all we have so we make use of it as we can, and at least it offers plenty of opportune shots for photographers.
There's a similar thing in Philadelphia...it's even more selective. The "L" is a specific subway line. There's the Regional Rail, then the Broad Street line, and the Market-Frankford line and it's the Market-Frankford line that is the "L". Took me several months to figure that one out! I digress...awesome image as per your usual. ;)
