"This calls for a mind with wisdom.1 The seven heads2 are seven hills on which the woman sits.
References for Revelation 17:9
They are also seven kings. Five have fallen, one is, the other has not yet come; but when he does come, he must remain for a little while.
The beast who once was, and now is not,3 is an eighth king. He belongs to the seven and is going to his destruction.
References for Revelation 17:11