Ah yes, the castle, a structure that serves many purposes and has a tendency to be impressive to us today. They come in a variety of styles, some of which seem a bit odd. But they also have a few different formats, the 2 most well-known being historical and fantasy. Historical castles are those that were indeed built at points in human history with their intended use of acting as some sort of fortification, while Fantasy castles are those that exist in stylings and details that are mostly there for aesthetics.

Here's a video to help better emphasize that,

also, this video

The videos can also probably help you with some of your projects.