The world of Aiwerond has an unusual geometry. The science, which studies it, and the world geometry itself, are called metageometry.
The most visible consequence of the special features of the world geometry manifests itself with the the so-called Mirror Line, in Quertílian Queriwóhri'on ("The Mirror of the World"), Islandish Štelekrí delek ("Line of mirrors"). Queriwóhri'on is also the international name.
The Mirror line
Maps, which depict the whole Aiwerond surface, have the form of a circle, with the Bieneialen insel and its unclimbable mountain in the centre. The boundary of this circle is the Mirror line.
Crossing the Queriwóhri'on, one finds himself at the exact opposite, "antipodal" point of the circle. That point can be identified by leading a direct line from the source point through the origin (Bieneialen mountain) across the whole disc. The other intersection with the boundary is the target point. Using polar coordinates with origin at the Bieneialen mountain, the target point has the angular coordinate complementary to 180°, but with a reversed sign, and the same radial distance.
What follows from the above, is that after crossing the Line, the left and right hand side are switched and - at the same time - from the view of any observers who didn't cross, the traveller is mirrored (unless they look at him across the Line). For example, if a traveller from Crakl-ring-söz follows the 90° line further away from Bieneialen, he comes at the -90° point near Hyarn. If he then continues the long way home without crossing the Line again, not only will the whole world, the continents, the mountains, his city, his house, his room and the people he reunites with be reversed for him, but his wife (who stayed home during his whole travels), will see him reversed. Right and left are not invariant in Aiwerond.
The side-switching doesn't cause any problems for any living creature, as the bodies of all aiweronian inhabitants (people, animals, plants, ...) are adjusted to that (birds, fishes etc. cross the Queriwóhri'on all the time). Since travelling across Queriwóhri'on has become frequent, people also don't make a big fuss about it anymore. It has become a normal part of their world.
In the Aiwerond universe, the microworld (subatomic particles, atoms, molecules, cells etc.) also works the same when mirrored i.e. all physical/chemical/biological phenomena observed at the macro level are chiral (out-of-universe note: this may not be true in our world, but Aiwerond is a fantasy world, after all, so take this as given).
The Mirror Line itself does not look anything special and as metageometrical models show, it could actually be centered at any point, as it can't be defined, which part of the world has the correct right-left orientation. However, with Bieneialen in the center, the line leads entirely through seas (there are three Eiqaterian bridges crossing it). This observation lead the Aiweronian scientists to further investigate the hypothesis, that the world in general and the Beneialen in particular are not of natural origin and may have been built by the assumed Eiqaterians, ancient Constructors of the World.
If you look across the Queriwóhri'on, you will see the land and sea behind the target point - mirrored of course, but not obviously so, as nothing gives that fact away from the distance. Crossing the Queriwóhri'on is nothing more spectacular than crossing any sea, the travellers notice nothing, there's no sudden change. As such, the world can be perceived as continous. There is no edge, one can travel any direction as long as one wishes and will not leave the Aiweronian Circle.
One question Aiweronian philosophers, physicists and many amateurs have been discussing since they've tried to understand the world by applying reason is: what happens, if the Mirror line is crossed by an object so large, that the curviture of the line is not negligible (the opposite is the case with anything people can built, people themselves can't perceive the curvature). Will the object be destroyed as it adjusts to the opposite curvature at the target point? The main metageometrical theory answers this question negatively. The models suggest, that shape of the world is actually relative to the position of the observer, so that the Queriwóhri'on actually is a straight line for anyone and anything crossing it. The aiweronian space is Euclidean only locally, it behaves unintuitivelly across long distances. This result is strange and has been put into questions by many, but the relativist nature of the world must be and is taken into account. For example, Hatlent's tables and the wéranthi'ols are examples of tools, which try to solve navigation problems caused by these properties of the aiweronian space.