The real reason the London Underground's 17-mile elliptical route is called the Circle Line?
Not because of its circulatory avenue, but because of its resemblance to one of the nine circles of hell depicted in Dante's Inferno.
Transporting some 117 million Londoners and tourists a year, it's the most congested, delayed and hottest line on the Underground - and architecture firm NBBJ thinks it's got the perfect idea to improve it.
Ditch the tracks, bin the trains, and replace them all with travelators - those motorised walkways that speed you along at airports.
The concept design would see passengers navigate between sets of travelators: a "feeder" lane, moving at three miles per hour would join a yellow "slow" lane - that would slow to three mph through stations, before moving up to between six and nine mph in lit tunnel sections. An orange middle lane would clock along at 12 mph and a fast lane would hit a maximum speed of 15 mph.
The travelator concept wouldn't radically improve the speed of a commute - current trains can complete a circuit in an hour, while the proposed concept would see passengers make a lap in 56 minutes. However, it's a healthier option than sitting for an entire journey, and would increase the capacity of the entire line three times over.
Moving seats would be provided for elderly or less-able users, though it's not entirely clear how they would move between lanes.
A concept that's almost certainly not going to see the light of day (it was designed as part of a challenge from think tank New London Architecture), what are your thoughts on the system?