C1 by Emma McNally. These subtle illustrations look like they could have been created using a complex computer algorithim or generative art software, but they are all meticulously hand drawn with graphite on large sheets of paper. The subtle textures and patterns have a beautiful, eery, astronomic feel to them.
The Antikythera Mechanism by Michæl Paukner -- This mechanism is an ancient mechanical calculator designed to calculate astronomical positions. It was recovered in 1900-01 from the Antikythera wreck, but its complexity and significance were not understood until decades later. It is now thought to have been built about 100-150 BC. Technological artifacts of similar complexity did not reappear until the 14th century, when mechanical astronomical clocks appeared in Europe.