If you’re going to keep your cat indoors, the best thing you can do is not let him/her know about the outdoors for as long as possible. Once a cat gets it into its head that it wants to go outside, you have a battle on your hands.
So I’m intrigued by this post on building an Outdoor Tunnel For Indoor Cats. Julia found a cat door that was made for windows, so she built a tunnel that runs along the fence of her garden and opens into a cage that sits under her lilac bush. Lucky cats!
Looks like they enjoy it, too.