Atlantes was a powerful sorcerer featured in the chansons de geste. The sorcerer built a castle of iron in the Pyrenees

Pyrenees

The Pyrenees is a range of mountains in southwest Europe that forms a natural border between France and Spain...

 to keep knights and ladies he had captured as a diversion for Ruggiero

Ruggiero (character)

Ruggiero is a leading character in the Italian romantic epics Orlando innamorato by Matteo Maria Boiardo and Orlando furioso by Ludovico Ariosto. Ruggiero had originally appeared in the twelfth-century French epic, Aspremont, reworked by Andrea da Barberino as the chivalric romance Aspramonte...

, a Saracen knight. Atlantes feared that Ruggiero would convert to Christianity

Christianity

Christianity is a monotheistic religion based on the life and teachings of Jesus as presented in canonical gospels and other New Testament writings...

 and aid Charlemagne

Charlemagne

Charlemagne was King of the Franks from 768 and Emperor of the Romans from 800 to his death in 814. He expanded the Frankish kingdom into an empire that incorporated much of Western and Central Europe. During his reign, he conquered Italy and was crowned by Pope Leo III on 25 December 800...

 against the Saracens as he had foreseen through the use of the Book of Fates. In Orlando furioso

Orlando Furioso

Orlando Furioso is an Italian epic poem by Ludovico Ariosto which has exerted a wide influence on later culture. The earliest version appeared in 1516, although the poem was not published in its complete form until 1532...

, Atlantes constructs a magical castle filled with illusions, in order to divert Ruggiero from what he has foretold as certain doom.