Something that came up on the former Twitter, Lagonegro was served (briefly) by two rail lines of different gauges, from two different directions.
Using Google Earth, exploring what was built to create the partly rack-operated narrow gauge route to the south east - all 100km of it, is... sobering, starting off with this viaduct by which it left Lagonegro in dramatic style, into a tunnel that involves a ~300 degree turn, exiting via a portal in the face of a cliff to rack itself uphill on a viaduct and into another tunnel. The viaduct still stands, by the skin of its teeth, having been racked by Bradyseism. It stands, precarious, above a void...
https://www.highestbridges.com/wiki/index.php?title=Lagonegro_BridgeMark