I can build everywhere -.-

Suddenly i can build everywhere in my TD, exept cliffs and water. All Towers require a "buildable" place but i can also build on every stone tile. And i tried some standard buildings but they are also buildable on stone. It works in WE unlimited as well as in the map itself. I don´t get it

I´m sure in older versions i could only build on grass.

You can make special Buildability Blockers - grab any Pathing Blocker and change its pathing map to Circle of Power - and make certain areas unbuildable with them.

This is in the wrong area... but anyway... Are you using Pathing Map - Arcane Tower etc. etc.? That COULD be a reason, but it's not a solid theory.

Also, are you SURE that the terrain tiles you're using are unbuildable?

Also, base it off a normal tower (Arcane Tower/Guard Tower/Cannon Tower) and try again, if it still messes up, something is wrong with the map's own pathing system OR you messed up the pathing of the structure in some unclear way.

o.0
In object editor.......
Select a building......
Scroll down to Pathing-Placement Requirements
Then choose one of the followings
Air-Pathable (I forgot what this do, maybe it's on cliff....)
Amphibious-Pathable (I forgot what this do)
Buildable (Normal building requirements)
Ground-Pathable (Builds on any ground, stone, unbuildable-stone tiles, etc.)
Sea-Pathable (Build on water)
Unblighted (Undead buildings need this to build on unblighted)
This Pathing section is a nice good place for custom maps.
WEU might have standard Pathing-Placement Requirements - *blank* I dont know, I don't use WEU, I just don't like the idea of making a new WE and making everything simplier when there's a challenging one in front of us made by blizzard, crappyly(might not be a word, but it will be one day).

Yeah, it is most likely, as the others have said, the plathable requirements, but you said thats right, the type of ground (unbuildable) and the Pathing Textures thing, all TDs use/should use the "Arcane Tower/Guard Tower/Cannon Tower" one. (4 by 4)