Bern visit

Yes there are, but of course it depends on a person's own interests.
You should read the official tourist website to see if there are activities and things of interest to you to warrant a 24 hour visit.
https://www.bern.com/en/home

Don't miss the Rose Garden to get a bird's eye view of Bern.

24??? More than that! I love Bern. Worth doing:

• Bern Munster (cathedral) and tower
• Zytglogge (giant cuckoo clock)
• general wandering through the streets of one of Europe's best-preserved medieval cities
• Bear Pit (although I understand if some have ethical reservations with it, we do too and found this a reasonable facility)
• Bern Historical Museum / Einstein Museum
• Tubing down the Aare river

Agree with many of the other suggestions. Just visited the History museum a few days ago and loved it. Terrific collections. Also because of all the embassies, Bern has a pretty cool dining scene. We found an Nepali restaurant that was top notch. I think you can definitely fill a day there.

Great responses! Thank you all!!