We don't want that now do we? Well then you will be pleased to know that there is a way to change it! Yay!
First you will need to locate the neighbourhood image that you want to change. You'll find this in My Documents>EA Games>Sims 2>Neighborhoods> then inside the folder that contains the neighbourhood you want.
The defaults are as follow. N001 is Pleasantview, N002 is Strangetown, N003 is Veronaville and if you have Seasons then G001 is Riverblossom Hills.
(I deleted Veronaville in my game which is why my custom neighbourhood is listed as N003)
Open up the neighbourhood picture that you want to alter with any picture editing program and make your desired changes. You can also make one from scratch if you want but you will have to save it as a PNG and if the size ratio isn't the same as the original the game will stretch it to fit.
In my example I have used several in-game pictures that I have pasted together.
You can see my new image is quite a bit larger than the original so I shrank it down and pasted it onto the original, flattened the image and then saved it back into the neighbourhood folder with the same file name.
Now the next time you load your game your new image will show instead. Say goodbye to your ugly SC4 terrain.
