On top of upgrading your characters the Cecillia are often used in Genshin Impact, while not that hard to find you'll still need a lot of them so here's a guide to where you can get your hands on a bunch.
Cecilia Location Genshin Impact
All the Cecillia of Genshin Impact are located in the exact same spot making it really easy to farm, those can also be brought in Mondstadt.
If you're looking for a more precise location for all these Cecillia I'd advice checking the official interactive map where you'll be able to zoon as you see fit.
You can find the map on the Hoyolab website here.
