Towers - are the still effective without walls


I believe I read a guide long time ago, but I want to make sure... scenario:
-Bireme City
-Build Tower and bring the wall to zero
will the tower still be effective and give the birs 10% bonus in defense?

I read some posts here and there that suggests either responses.
BTW, the simulator suggests that tower without a wall gives the defense bonus.

Thanks in advance


Yes it is like the harbor having the requirement of the level 15 timber . Once the harbor is complete at level 30 . You can demolish the timber all you want without losing the harbor . So one would think it should apply to the tower too .