Nevertheless, Viollet-le-Duc could not resist placing a few tiny references to himself in the restored architecture. He rebuilt the central spire of the cathedral, which had disappeared in previous centuries, and when he did so, he surrounded the spire at its base with statues of religious figures (mostly apostles). All of the figures are noble and solemn, except one ... namely, a statue of Viollet-le-Duc himself! In theory the statue is of Thomas the apostle, but in fact Viollet-le-Duc was the model.
The statue is on the southeast corner of the central spire; it is the topmost figure on that corner, as you can see here. Note that all of the figures are looking down at the ground below, except for the statue of the architect, which appears to be looking up in amazement at the architect's own work. Notice also the yardstick that he is holding in his hand, and his hair style, which at a distance looks mysteriously like an engineer's pith construction helmet. This is his subtle personal signature on the restoration. It is only visible if you are explicitly looking for it, but once you have seen it, it is hard to miss or ignore.
