The mountain-crossing section of the Madrid-Valencia line is also noteworthy for a tragicomedic legal battle. A timebomb from Aznar times (when every project was rushed), the section's environmental study was annulled by courts, on multiple instances, because it just didn't address the impact on a traversed natural reserve(!). All the while, construction was on-going and is now practically finished. (Google Translate is not enough for me to get the legal niceties.)

A little to the west from the Viaduct of Istmo, the Madrid_Valencia line crosses the Contreras Reservoir over the Contreras Viaduct (main span: 261 m, 37 m high); again with ADIF's class 355 diesel test train. Photo via user Dutch Mentor from URBANITY.ES.

_{*Lunatic*, n.
One whose delusions are out of fashion.}