>Halfway through, a sundial shows the time. I'd love to know how that works in a tunnel!
Apparently it's quite the impressive underground sundial.
https://bicyclenetwork.com.au/newsroom/2023/03/30/worlds-lon...
https://www.smithsonianmag.com/smart-news/the-worlds-longest...
https://edition.cnn.com/travel/article/worlds-longest-cyclin...