Presents Byzantine lead seals from the Ficoroni collection, as featured in his book I Piombi Antichi (Rome, 1740), along with papal lead seals from the same collection. Several obvious errors have been corrected, and transcriptions of numerous legends have been added. Finally, a description of the well-known seal of Hagia Sophia in Constantinople, first described by Francesco Ficoroni in the same book, is included as an appendix.