Add like leaves and vines that slowlly grow on the outside of the base depending on how old the base is. It is also a good idea that the vegitation is diffrent in every biome. It will make bases look way more naturall and just like in real life you will be able to tell about how old the base is.
Maybe make it so if a base is decaying it starts to get vegetation growing on it since an active base is being constantly upgraded n stuff. But the idea is cool
Radics Noel very amazing idea.