I live in an apartment in a large city, so I can't let my cat out because he would get lost or run in front of a car. It is a young and very curious cat, so he naturally wants to get out and explore.
He spends a lot of time just sitting in front of a window, staring out, sometimes crying loudly because he can't get out. I bought him a guide, but he doesn't like wearing it (a lot).
What could I do? Is there any way to satisfy the cat's curiosity without letting him out?