This article systematically verifies a series of properties of an ancient figure called the arbelos. It includes some new discoveries and extensions contributed by the author. ‡ Introduction Motivated by the computational advantages offered by Mathematica, I decided some time ago to embark on collecting and implementing properties of the fascinating geometric figure called the arbelos. I have since been impressed by the large number of surprising discoveries and computational challenges that have sprung out of the growing literature concerning this remarkable object. I recall its resemblance to the lower part of the iconic canopied penny-farthing bicycle of the 1960s TV series The Prisoner, Punch's jester cap (of Punch and Judy fame), and a yin-yang symbol with one arc inverted; see Figure 1. There is now an online specialized catalog of Archimedean circles (circles contained in the arbelos) [1] and important applications outside the realm of mathematics and computer science [2] of arbelos-related properties.Many famous names are involved in this fascinating theme, among them Archimedes (killed by a Roman soldier in 212