Were the Novia Sewers built by a race of Giants ?

While making my way along the underground passage to the mines, I came to muse upon the various gates in my path.

And I have come to the conclusion that the early humans that built these expanses were either 10 feet tall, or used extensive Troll slave labor during construction.

And what is with the size of that key hole ? The key that fits in that slot must be as big as my hand.

Ah, the stories these halls might tell...