The Antikythera Mechanism, now 82 small fragments of corroded bronze, was an ancient Greek machine simulating the cosmos as the Greeks understood it. Reflecting the most recent researches, A Portable Cosmos presents it as a gateway to Greek astronomy and technology and their place in Greco-Roman society and thought. A Portable Cosmos is both an excellent focussed case study of an individual object and a comprehensive broader treatment of the relevant aspects of ancient science and technology. It is beautifully and thoughtfully illustrated, with numerous diagrams and photographs placed strategically throughout, not just of the mechanism but of various other relevant ancient objects such as calendar and other almanac-style parapegma inscriptions, manuscripts, astrolabes etc. I shall definitely be adding it to the syllabi of my 'Nature and the Natural World in Antiquity' and 'Ancient Technology' courses, and I recommend that other instructors do the same.