And last but not least not a tunnel: The Avon Aqueduct.
Both – the Falkirk Tunnel and the Avon Aqueduct – are a bit scary. The tunnel because of "slippery when wet and slimy" (I managed to cycle through though but I wouldn't do it again). The aqueduct because the paving is so rough and the tow path so narrow that you risk to fall into the canal.
https://en.wikipedia.org/wiki/Avon_Aqueduct
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The Union canal ends within the city centre of Edinburgh!
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The next one is one of the french just to add one more to both of your lists. It wasn't far from your route, @taseroth :) – it's the voie verte du canal du midi à Montségur and features automagic lighting as well. There's a 2nd tunnel too.
I was pushing that day to reach Montségur via a different route so I took only 1 pic.
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I encountered some nice tunnels during my #mdrzaucf202406 (#mdrza with "detours") - first the one in #scotland:
The Falkirk Tunnel of the Union canal tow path (636 m).
With route 754 there is an entirely traffic-free cycle path from Edinburgh to Glasgow. It runs along the tow path of the Union and Forth & Clyde canals. Latter is pretty fast, the Union canal section could use some maintenance (roots).
https://en.wikipedia.org/wiki/Union_Canal_(Scotland)
https://en.wikipedia.org/wiki/Forth_and_Clyde_Canal
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