The architects who designed it actually created an "optical" illusion.
An optical illusion is a illusion affecting the visual framework and described by a visual precept that seems to contrast from the real. When we see a thing, the manner in which we see things in a particular territory varies essentially relying upon our angle and perspective. To neutralize it, numerous designers make an optical Illusion and it will invalidate the impact of the distortion.
Its ether the violin or viola
Its the chords and kind of the vibe the song gives. basically chord progression that has a pleasing effect.