It's one of questions for my exam, and I couldn't find anything about inversion related with architecture on the internet. Thanks for help!
Hard to say without knowing the material covered in the course. However, it could be referring to Robert Hooke:
As hangs a flexible cable so, inverted, stands a rigid arch.
Which describes a way to find the funicular form for an arch by inverting the shape of a hanging cable under the same loading. In other words, experimental form finding!