Mr. O'Toole had noted this, but, having been a big fan of Larry Niven's Ringworld (and, to a lesser degree, its sequels) in my misbegotten youth, I decided to see it for myself.
It is impossible to get a good sense of the size of the Ringworld, given limitations on draw distance and our general inability to grasp the size of immense objects, but creator Jimbo Perhaps has done his best, placing the Ringworld within the context of more familiar objects.
The Ringworld (outer ring, at left) and shadow squares (inner ring, center)
General Products hulls. From L to R: #1, #2, #3, and #4 hulls