Below Cliff Drive you can still find remnants of structures that pre-date the creation of North Terrace Park now Kessler Park. A lot of large stone walls remain, foundations of other buildings, even the remains of streets. This is a small sample of what exists... after the bush honeysuckle drop their leaves I'll venture forth to get more photos.
Above, old foundation, below, who knows. I'm gonna go with Aztec.
This large wall seemingly has no purpose that I can see.... may have been intended for erosion control.... but, in lieu of knowing for sure, I'm going to, once again, go with Aztec.