I don't know much of anything for sure. I mentioned on another thread about the legends of my little mountain village, that not far away an indigenous tribe ran a protection racket for the merchants who traveled from Oaxaca to Tenochtitlan.
Part of the legends my wife heard in the 50's as a little girl was that Moctezuma came out once a year to receive tribute from that indigenous tribe after they conquered them around 1500. And, the tribute was gold. Thus, I imagine the toll paid by the merchants may have been in gold.
Part of that legend was the statement that prompted a belief here in buried treasure. The people were allowed in the house in the daytime, and they would see the local chiefs pay the gold tribute. Then at night, the people would be forced out, but would watch all night to see if anyone came out.
The next day when they went back in the gold would be gone. Thus the original buried treasure legends, though this was different from the Moctezuma treasure legend.
Another legend was Moctezuma had tunnels built from here quite a distance away in case he was sieged, he could escape.
I can accept tunnels of a few hundred yards, yes. Although no one has found any such thing.
But, these mountains are made of travertine marble, which is not a true marble, but makes a nice floor.
Travertine is wet. Travertine marble mountains are full of water. No tunnel could go the distance they claim without soon filling with water.
So, this is one legend I do not at all believe.
However, should I ever find myself with a ground-penetrating radar set under my arm, heh, heh, right after I scope out the Tomb of Moctezuma, I will scan the ruins for tunnels.