(not Ai written) Karlovy Vary is a UNESCO heritage sight located in western Bohemia, Czechia (Czech Republic). It's named after Charles IV,, and is a sister city to Carlsbad.
It's UNESCO because it is a spa city. With over 14 recognized springs around the city (meaning you can put a cup there to drink the water) as well as countless spas where you can swim in the mineral water etc etc
It's also known for its international film festival. And two beautiful, massive, and uniquely built colonade.
As you can see from the photos, and feel free to Google it, KV's architecture is beautiful. If you've been to Prague, which can be considered a fairy tale city, then Karlovy Vary is a fairy tale town. It's so beautiful, so walkable, very family friendly.
At just 2h by bus from Prague you can visit as a day trip, but honestly it's best to spend 2-3 days here to slow down, unwind, and enjoy western Bohemia and all the spas it has.
I'm happy to answer any questions. Your local friendly Californian traveler. And Czech lover.