The significance of certain archaeological discoveries is not always immediately understood. This was exactly the case in 1901, when divers recovered a mass of corroded bronze from a shipwreck near the coast of Antikythera. No one could have imagined at the time that the oldest analog computer had just been discovered, an astonishing mechanism that once simulated the movements of celestial bodies as conceived by ancient Greek astronomers, and became known as the "Antikythera Mechanism". In addition to the chronicle of this incredible discovery, the author of this book explains in detail how the Mechanism worked, how it was constructed and for what purpose, as well as how it ended up on the ship that sank off the Greek shores around 60 BC. This groundbreaking work of engineering was also one of the earliest portable teaching aids. The technology it incorporated is the most advanced encountered in classical history by modern scholars, and it also revealed remarkable insights into Greco-Roman astronomy and scientific technology, as well as their place in ancient Greek society. Written by a world-renowned scholar of the Antikythera Mechanism, the book "A Portable Cosmos" will captivate all readers interested in ancient history, archaeology, and the history of science and technology.