This paper deals with the exact constructions of the regular heptagon in Greek and Arabic geometry, which are preserved in a number of mainly unpublished Arabic manuscripts. Appended are editions of the Arabic texts and English translations of Propositions 17 and 18 of the “Book of the Construction of the Circle, Divided into Seven Equal Parts”, attributed to Archimedes, and of the “Book on the Construction of the Heptagon in the Circle and the Division of the Rectilineal Angle into Three (...) Equal Parts” by the 10th century geometer Al-Sijzi. (shrink)