Was the Herodium hill a natural geologic formation or a man-made construction?

Question

Herodium is the site of one of King Herod's castles and now the presumed site of his grave.

Answer 1

Both.

Flavius Josephus, a 1st-century Jewish historian, wrote :

"a hill, raised to a (greater) height by the hand of man and rounded off in the shape of a breast."

Answer 2

The hill was natural, the city man-made.

Answer 3

It is a natural hill, but sculpted by man.