The infrastructure needs of any city or town—whether it is long-established or built from scratch—can result in beautiful combinations of art, architecture, and engineering. However, not all things go to plan. Sometimes, great ideas devolve into folly, expensive puzzles left incomplete or inadequately suited to people’s needs. Sometimes the line between awe-inspiring and groan-inducing can be perilously slim—or completely non-existent. 

Soaring over the La Paz–El Alto metropolitan area is a vast aerial transportation system like no other. The Mi Teleférico was the first urban system to fully utilize cable cars as a primary method of public transportation. The system, designed to combat pollution and traffic, made travel between two Bolivian cities, separated by a 1,300-foot slop, much safer. It’s a wonder, and basically the opposite of the Magic Roundabout in Hertfordshire, England. Once called “the second-worst roundabout in the United Kingdom,” this twisted roadway has confounded motorists for decades. It is more than one large roundabout, but six smaller roundabouts where cars travel in both directions. Good luck, motorists. From an incomplete freeway bridge to another that solves a high-rise problem, here are a few of our favorite wonders and blunders of urban planning.