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What was once the biggest railway station in Europe is now a decaying shell overlooking train tracks smothered in weeds. Canfranc International Railway Station opened with much fanfare in 1928. Sprawling, glamorous, and equipped with a ritzy hotel, it was the centerpiece of a railway line between France and Spain.

During the early stages of World War II, the train route became a lifeline for Jews desperate to escape occupied France. But within a few years, the Nazis took control and a swastika flew above the station. Under Nazi control, gold plundered from murdered Jews left occupied France on the line bound for Portugal and Spain. After the war, Nazi war criminals slipped through allied hands on these same rail lines.

A train derailment in 1970 lead to the abandonment of the railway line and its elegant Art Nouveau station. Canfranc Estación saw little activity until 1985, when Spanish physicists took advantage of its remote location and abundant subterranean space and opened the Canfranc Underground Astroparticle Laboratory. Here, beneath the husk of a former transport hub, scientists conduct experiments on dark matter, neutrinos and geodynamics.

More on Canfranc Railway Station can be found on Atlas Obscura.

Deserted railways:

• After seven years of construction, Cincinnati's subway tunnels were abandoned
• The now overgrown Petite Ceinture railway circling Paris operated from 1862 to 1934
• London's Post Office Railway -- commonly known as "Mail Rail" -- shut down in 2003

More on Canfranc Railway Station can be found on Atlas Obscura.