The back main (central) panel represents Christ enthroned flanked by angels with a kneeling Cardinal Stefaneschi at his right foot.
[5] Giotto represents the martyrdoms of Peter and Paul as taking place in recognizable locales, frequently visited by pilgrims to Rome.
Peter's crucifixion is placed between the Meta Romuli (a pyramid near the Vatican, destroyed in the 15th century) and the Terebinthus Neronis (a classical monument, likely a mausoleum, that no longer exists), while Paul's beheading is outside the city, near a round building that represents the church of San Paolo alle Tre Fontane, the site of the Saint's beheading South of Rome.
Stefaneschi is dressed in full ceremonial costume as a cardinal on the front, appropriate for the "public" face of the altarpiece and is introduced to St. Peter by St. George.
[7] The depiction of Stefaneschi holding this very painting suggests that it originally had a significantly more elaborate frame, which would have made the relatively small altarpiece fit better into the large space that was Old St.
[citation needed] The characteristic of containing a smaller version of itself provides one of the earliest known Renaissance examples of the so-called "Droste effect", common in medieval art.