Here's the original photograph, without the benefit of human scale, which is how it is intended to be seen and which leads to the trompe l'oeil effect of a long, grand hallway.
Layne helpfully walked into the scene in order to demonstrate Borromini's ingenious trick of the eye. The hallway is actually only about 20 feet long, with a steep uphill grade. The furthest columns are dramatically shorter, and the coffered archway narrows significantly while sloping downward (itself a masterful construction) as sharply as the floor rises, leading toward the statue which is barely a couple of feet in height. So maybe Borromini was onto something after all with his architectural ideas, despite the lasting disrespect he gets from Rome's urban mythology.