4Japan's Kimon Corner
I don't know whether Japan's spirits are like the Chinese ones and thus can't navigate corners or whatever, but I can tell you they all come from the same direction -- the northeast, or "kimon." Kimon means "demon gate," and is where the bad spirits come from. As you can guess, that would be a bad place to put a door.
The view would be terrible.
It would be a good place, obviously, to put something like a guard tower. Hiji Castle, for example, has a kimon tower on the northeast side, to guard against evil spirits. They even cut off the kimon (northeast) corner of the kimon (northeast) tower to be extra safe, somehow.
I guess that's kind of smart, actually. Structurally, a corner is a weak point. Flattening it off means it can stand up to more damage from demons before it begins to break down. I have no idea what kind of calculations you'd do on a structure to measure how much spiritual damage it can withstand, but you know what? I'm not an ancient Japanese architect. I'm not going to tell them how to do their job.
Say you're an average Japanese person. You live in an apartment. You can't build a fucking tower. How are you going to ward off spirits to protect your home, your family/robot companion and your spouse/pillow with a picture of an anime girl on it? Well, I guess your landlord is responsible for making the building kimon-safe on the outside, and the only way the spirits will get into your apartment is through your plumbing, so that's why it's a pretty big deal to not build a bathroom in the kimon corner of your apartment. I guess this is something quite a few Japanese people still actually care about.
Because nobody wants ghosts in their apartment to begin with, but if anything could make that worse, it's probably a ghost crawling into your apartment covered with an entire apartment building's worth of sewage.
3Thirteenth Floor (And Floors that End in Four in China)
"Wait a minute," you might say. "The number 13 is not a ghost." You are clearly someone who has never had to wake up to the number 13 rattling its chains in the next room or causing your child to say "REDRUM" over and over again. Anyway, unlucky numbers are specific concepts that people believe will do horrible things to them in a magical way, so close enough. If you're insistent on ghost purity, read ahead to the next entry.
Most people have heard about some Western buildings not having a 13th floor due to superstition about the number 13. The practice has been dying out, but some newer buildings still do it, like One Canada Square, the tallest building in Britain (until the Shard London Bridge is completed).
Doesn't really have much else going for it, does it?
One Canada Place gets around the problem by having no "usable space" on the 13th floor, and no button for it on the elevator. Other buildings just rename the 13th floor as "14," exposing the unsuspecting residents of the new "14th floor" to all kinds of magical catastrophes, unless the number 13 spirit is as stupid as a Chinese ghost and just wanders away disappointed after not finding its designated floor.
Speaking of China again, Chinese buildings are even better. The unlucky number in China is four, as well as any number that ends in four. Why? Because the word for "four" sounds like the word for "die". Yes, that's a superstition based on a pun. I think that accounts for about half the superstitions in China. Like the word for "orange" sounds like the word for "gold," so you eat oranges on the New Year so you can be rich. Anyway, so no fourth floors.
And on many buildings, no 14th floors either. And no 24th, 34th, etc. But wait! There's more.
China is part of the global economy now. That means they're picking up Western habits, like smoking, pollution, getting fat and a ridiculous avoidance of the number 13. So you can find buildings that are missing not only the fourth floor and 14th floor, but also the 13th floor.
I think the -1 floor here might have been an attempt to offset the missing floor four, but throwing out floors 13 and 14 kind of makes that whole exercise pointless, you'd think.
So yeah, it seems pretty silly, until you look at one study saying that Chinese and Japanese (who share the superstition) populations actually show a spike in heart attacks on the fourth of each month, apparently literally scaring themselves to death. The study has been disputed, but you can't say the number four isn't serious business in Asia.