Final answer:
Ancient underwater 'skyscrapers' are not man-made but could refer to natural coral formations or metaphorically to the constructions of ancient peoples who built complex monuments and temples through remarkable creativity and without modern technology.
Step-by-step explanation:
The underwater skyscrapers of the ancient seas on Earth were not built by a specific entity; rather, these remarkable structures often refer to natural formations such as coral reefs or, metaphorically, to the impressive achievements of ancient civilizations who constructed large-scale monuments and buildings. The ancient peoples, through remarkable ingenuity and creativity, built monumental structures like temples, palaces, and sites such as the Sanctuary of Asklepios on Kos, without the aid of modern technology.
Throughout history, as civilizations flourished, new specialized occupations emerged, and the demand for more sophisticated structures grew. The ancients crafted elaborate frescos like those in the Palace of Knossos, reflecting their environments and economic activities. This evidence from archaeology and history demonstrates the ancient people's capability, comparable to ours today, even in the absence of modern conveniences such as electronic textbooks.