Canary Wharf in London has a installation of six Swiss railway clocks which, invisible to most people passing by, has a clever way of synchronising.
https://www.ianvisits.co.uk/articles/see-londons-six-swiss-r...
> The second hand takes 58.5 seconds to rotate around by 59 seconds, then the second hand pauses. It waits until a nationwide pulse is sent to every Swiss railway clock that a minute has passed, then the clock jumps to the minute and carries on for another 58.5 seconds.