It took Ghiberti 21 years to complete these doors. These gilded bronze doors consist of twenty-eight panels, with twenty panels depicting the life of Christ from the New Testament. The eight lower panels show the four evangelists and the Church Fathers Saint Ambrose, Saint Jerome, Saint Gregory and Saint Augustine. The panels are surrounded by a framework of foliage in the door case and gilded busts of prophets and sibyls at the intersections of the panels. Originally installed on the east side, in place of Pisano's doors, they were later moved to the north side. They are described by Antonio Paolucci as "the most important event in the history of Florentine art in the first quarter of the 15th century".
The panels are included in a richly decorated gilt framework of foliage and fruit, many statuettes of prophets and 24 busts. The two central busts are portraits of the artist and of his father, Bartolomeo Ghiberti.
Although the overall quality of the casting is exquisite, some mistakes have been made. For example, in panel 15 of the North Doors (Flagellation) the casting of the second column in the front row has been mistakenly overlaid over an arm, so that one of the flagellators looks trapped in stone, with his hand sticking out of it.[8]
Michelangelo referred to these doors as fit to be the "Gates of Paradise" (Porte del Paradiso), and they are still invariably referred to by this name. Giorgio Vasari described them a century later as "undeniably perfect in every way and must rank as the finest masterpiece ever created". Ghiberti himself said they were "the most singular work that I have ever made".