Final answer:
The discovery of thousands of ancient objects best supports the notion of Tenochtitlan as a vast treasure, revealing cultural, religious, and historical riches.
Step-by-step explanation:
The detail that best supports the idea that the ruins of Tenochtitlan are a vast treasure is the discovery of thousands of ancient objects. These findings suggest the city was not only a center of powerful civilizations such as the Aztecs but also a site where valuable artefacts and evidence of sophisticated culture, religion, and social structure can be found. The richness of the discoveries, including stone urns, gems, a panel with rows of skulls, life-sized Aztec warriors made of clay, and a stone eagle for sacrificial rituals, all add to the understanding of Tenochtitlan as a treasure of archaeological and historical significance.