The ones that overlap territories and have more than 4 tiles, what do they actually do?

The wonders give the owning city more stability.

All natural wonders provide +5 Influence, +10 Stability and +10 Gold to the territory they are located in. Most wonders take from 2 to 4 tiles but they are always located in a single territory as far as I know.

I mean the big ones that are like 20-30 tiles and overlap on territories.

Or do they have a different name, not "natural wonders"?

Those are Landmarks, and doesn't do anything no, they are just big forest, rivers, desert etc that are remarkable by their sheer size.

I think you can destroy at least the forest by cutting them, not precisely sure what we do if you nuke desert landmark though (to me we should destroy it if enough of it is wasted but I'm not even sure ^^).

Oh, thanks. Too bad they have no further effect. :/

One thing about the Landmarks, when I zoom out, I can see the name of the landmark Forests, but Mtn Ranges, Lakes, Rivers, Deserts I have never seen a title after zooming out.

Krikkitone wrote:

One thing about the Landmarks, when I zoom out, I can see the name of the landmark Forests, but Mtn Ranges, Lakes, Rivers, Deserts I have never seen a title after zooming out.

Yes, there's that, too.