Slow, rubbish service on the London Underground.
Users of the Circle line see absolutely no irony in the fact that it goes round and round without any real defined final destination. Mainly used by buskers so they only have to pay for one ticket but can stay on the train and annoy people all day.
The only real benefit of the Circle line is that it allows you to be indecisive.
The Circle Line achieves a truly revolting ECUC of 80%.
Stations on the Circle Line
Other Circle Lines
There is also a bus route in Adelaide called Circle Line. It goes in a giant circle around the outskirts of the city. It's really more of a rectangle. Regardless, the bus fails to pull over and let anyone on or off and just continues to speed around oblivious to it's designated role in society. If one finds oneself on the Circle Line bus then Friki advises you jump when you near the corner of Cross and Portrush roads. Theres a park there for a nice soft landing, a vet clinic nearby incase you miss the park and a church is right on the corner incase you land on your head and have all the sense knocked out of you.