Algo for rotating tower towards enemy - Unity

[haroonalam]

Hey ppl, I have made a grid and placed towers and moving a enemy on it.
Now i want to rotate towers face towards enemy when enemy comes in the range of tower.

I have a solution that whenever enemy comes to its range ( 2 grids far ) it starts do something, lets say when tower finds enemy is on left side it starts firing like that when enemy moves up/down ( when it finds there is a tower on very next tile) tower starts rotating with enemy position uniti enemy’s range that is 2 grids far. So its mean tower has to rotate whenever enemy comes to its range and moves up/down.

What would you people suggest me a optimized way or any helpful scripting function ?..thnx

[system]

if(Vector3.Distance(transform.position, enemy.transform.position) < 2)
{
transform.LookAt(enemy);
}