Calling them "castles" is a bit of an aggrandizement.
They are essentially an installation that allows visitors to take carefully cropped photos to be posted on social media. These are mine:
The location's pamphlet F.A.Q. includes the question: "Will an icicle fall on me?" Answer: icicles attached to roofs fall, icicles attached to ice will only melt on you.
And for the sake of posterity, this is what visiting the Ice Castles is actually like in person: