3 Answers

The "Clem 7" tunnel thru Brisbane (Australia).Cost $6 Billion & no one will use it because the toll is too expensive.The company that financed it has gone broke & we are stuck with it.

I would like to nominate the internal combustion engine, which is only 15% efficient, the other 85% being dissipated as heat. The principle of a piston moving up and down in a cylinder dates back to the earliest steam engines. Some of these spotty teenage geeks in their Californian garages would be much better employed  thinking up a better engine instead of poisoning our computers with their viruses.

chernobal russian nuclear power plant that meltd down,30 years later still feeling the effects.