Front Gate of the Ominous Building
Not much is known about this place, and hopefully more light will be shed upon it later, however the guards are all extremely high-level. It hasn't been said if this location is going to have some use, but it's appearance in the game itself signifies some type of meaning. Only very few people have told they have seen a woman (called Ominous Girl) roaming inside the facility.
For all that's known, it could be some kind of magical GM-Meeting spot. Doubtful though, it's likely an event location that's yet to be used, seeing as no one seems to know anything about it.