Striving for physical consistency in a mythical realm
Why is it a problem if an evil wizard live in castles just like those built by the real life Catholic crusaders in the Middle East? We can restate this problem by saying “why is it a problem if a magical Harry Potter learns magic at a normal school?” In both cases the answer is the same. The architecture should reflect the powers and nature of the “special” that inhabits it.
But although it is obvious to many why that is the case with Harry Potter, they fail to understand why that is so with the evil wizard. To many people a castle is an exotic location in a medieval time period. They reason that since a wizard is a creature of power from a medieval time period then an evil wizard would naturally make his home in a medieval seat of power. If a myth creator is feeling like being especially “realistic” they will research how real castles look and functioned so as to get all the little details right. But many myth creators seem to feel that if it has walls and towers and a keep then a generic castle is good enough for their audience.
And this belief has some basis in fact. Few people will read a story and think “this castle really does not fit with what we know of this evil wizard.” But even fewer people reading a story with an evil wizard in a typical castle will remember either the castle or the wizard for long. They might not know anything about castles, but they can feel when a character and setting do not reinforce each other.
Therefore a good myth creator will not create castle for his evil wizard by copying historical castles. Instead a myth creator will think about what a historical castle represents. The myth creator will note that castles represent fear. When fear was not present, nobility built palaces and not castles. Castles also represent the technological ability of the time. A Norman motte-and-bailey is very different from the later Norman castles. And lastly, castles represent the culture and values of those that built them. A Norman castle looks very different from a Japanese castle and has different spaces in it (perhaps a large chapel in the Norman castle and an ornate tea room in the Japanese castle).
With the above thoughts is mind, a good myth creator will then create the castle for his evil wizard by asking “What is the evil wizard afraid of? What does the technology of my world allow (taking special care to keep in mind the special powers of the evil wizard)? And how do I represent values and culture of my evil wizard?” By asking these questions, a myth creator will create a castle that is far more memorable and believable then if he had tried to use either a “realistic” or a “generic” castle.
It must be admitted that the difference between a generic and a believable castle is hard to understand in the abstract. It is like trying to understand the sound not heard by listing to the silence. It might help to compare the difference between Moria in the Lord of the Rings and the goblin caves found in the Hobbit. Both places were created by the same author. Both involve underground tunnels and caverns inhabited by dangerous creatures. But one was generic and one was believable.
The goblin caves in the Hobbit are “generic.” Mr. Tolkien did not put a lot of thought into them and they don’t stand out from any other goblin cave anyone else might create. There is no details about the goblin cave other than it was a system of tunnels that had goblins in it. On the other hand, Moria was created with a lot of thought and so Moria has come to personify what a fantasy dungeon should be.
Because Mr. Tolkien thought through the implications of Moria, he created such details as underground defensive bridges, wells inside guard rooms, and a reason for why such things came to be abandoned by their creators. And these details did not spring up randomly or by copying something to make it “realistic”. Rather they sprang up from Tolkien’s efforts to make Moria physically consistent with the character of the dwarves and the threats they faced in the world they lived in.
Good myth makers can sometimes get away with a “generic” goblin cave if the other elements of their myth are good enough. That makes less talented myth makers think that all that is needed is a “generic” goblin cave. As a result, most myths are set in forgettable worlds and in turn are forgettable themselves. Only the best writers can get away with being generic and even they can only get away with it in small doses.