The Steyregg Castle we see today dates back to medieval times, with the massive tower houses dominating the bailey. In the course of time, the outside of the Castle was radically altered by fires, augmentations, and demolition - and it was almost let gone to rack and ruin. Although the Castle has been completely changed one can still see that it was once built to last the centuries, with thick exterior walls.

Source: https://www.donauregion.at/en/austria/poi/401928/steyregg-castle.html