Park Guell Architecture Illusion

This is an excellent photo. The architecture and the person blend to give the viewer a slightly brain bending feeling.

What is happening in this photo?

The below image is part of Park Guell in Barcelona. The Barcelona Tourist Guide says the following:

Park Guell was commissioned by Eusebi Güell who wanted to create a stylish park for Barcelona aristocracy.

Guell park contains amazing stone structures, stunning tiling and fascinating buildings. (read more)

Parc Guell by Antoni Gaudi
Copyright 2005 Müjgan
Used w/permission

The above building is leaning like this by design and the person in the photo leaning back against the building just adds to the dizzying effect that this image creates.