Croydon Ring Road

Admittedly the roads of South London are awful. The brown urban smudge that fills the gap between the Thames and the North Downs, twenty miles wide and twelve deep, is almost entirely bereft of decent roads. Trying to reach, say, Streatham from any direction by road means a long, tedious drive through residential streets and shopping centres. Croydon, the biggest commercial centre in the south of London, looks more promising on a map.

Its box of town centre dual-carriageways form three sides of a never-completed ring road scheme. But despite the piles of cash spent on them, the scores of houses bulldozed to make space for them, and the colossal viaducts and other engineering feats that carry much of the route, it's a terrible road system. It's only bearable because, buried in the mire of South London, its surroundings make it look heavenly.

Slow, ugly, divisive, intrusive and entirely lacking any sort of joined-up planning, Croydon's ring road is a lesson for highway engineers everywhere. Do what you like, but please, don't do this.