Stairway to heaven?

William Blake wrote, 'If the doors of perception were cleansed every thing would appear to man as it is, Infinite.' This door is actually just an ornamental hollow leading nowhere, but it's part of an instrument that's allowed many generations a glimpse into infinity. The Jantar Mantar of New Delhi, built in the 1720s on the order of Jai Singh II, is a complex of building-sized astronomical tools—including the structure we're seeing, which flanks a 70-foot-tall sundial aligned with Earth's axis. Other buildings on the grounds used strung wires to cast shadows or pinholes to track sunlight. Remarkable on its own, this is just one of five Jantar Mantar that Jai Singh—a known math and science buff—commissioned across his kingdom. Four still stand today, including this one, a larger one in Jaipur, and one each in Ujjain and Varanasi.