India’s baolis --stepwells-- are a marvel. These functional architectural gems were built for harvesting rain and cooling air. Many of these water reservoirs became sites of worship. Steps, platforms, columns combine in geometrically complex structures plunging into the earth, like an inverted building. Scattered across Rajasthan, Delhi, Gujuart and other parts of India, baolis date to 200 BCE. Here's a few images of these amazing structures.