unity rotate around point

var rotationVector = transform.rotation.eulerAngles;
rotationVector.z = 0;  //this number is the degree of rotation around Z Axis
transform.rotation = Quaternion.Euler(rotationVector);
//if you put this in a coroutine and yielding for some amount of time 
//you can have something like a rotating loading icon

Quaternion.RotateTowards(Quaternion from, Quaternion to, float maxDegreesDelta);

RoatationVar = Quaternion.Euler(Vector3.up) * camera.rotation;

transform.Rotate(axis, degrees);

transform.RotateAround(point, axis, degrees);