There’s no way to tell beyond pure guessing, as the gardens (or rather, the ruins thereof) have never been found, nor has any actual archaeological evidence of their existence.
Given the descriptions of them by some ancient writers, it would have to have been quite a lot, as they were said to be terraced on as many as four levels, set on stone columns, and large slabs of stone were laid under the planted terraces to prevent erosion of the soil. As the weight of all the plants, earth, and stone would have been immense, the columns and supporting structures would have to have been equally huge.
Given the descriptions of them by some ancient writers, it would have to have been quite a lot, as they were said to be terraced on as many as four levels, set on stone columns, and large slabs of stone were laid under the planted terraces to prevent erosion of the soil. As the weight of all the plants, earth, and stone would have been immense, the columns and supporting structures would have to have been equally huge.
