The T3 Tram around Paris

 
Extension of the T3 line around the periphery of Paris has been a wonderful development.  We now have corridors of green where once there was just asphalt (and, before that, squatter settlements built on the traces of demolished city walls).  The T3 line has also given a new "identity" to places that were already there, but had never been graced with the name of a transit stop (one example above).

Despite some lingering peak-hour capacity problems, this new tram system if one of the best things to happen to Paris in many years.  It is spawning renewed retail and residential vitality wherever it passes.  Proximity to the new tram has now made "desirable" parts of the 20th arrondissment that -- for most of the 40 years I've known them -- had been left to degrade into squalor.

http://www.ratp.fr/en/ratp/c_5045/tramway/