Of course what used to be known as The Innocent railway is now a cycle path
It was built to haul coal from the Lothians ( mostly Dalkeith and Newcraighall ) into Edinburgh
The cycle path bit starts around Asda at Brunstane, goes along Magdalene, crosses Duddingston Road at forkenford then along round Arthurs Seat to St leonard
http://www.youtube.com/watch?v=cJOF0_XshbkThink the formal name was Edinburgh and Dalkeith railway
for some of the old routes see
http://en.wikipedia.org/wiki/File:Edinb ... RJD_27.jpg