"the gloomy circle of some Inferno"
Ilustration from Dante's Inferno
Public DomainIllustration from Dante's Inferno - Credit: Gustave Doré
Dante Alighieri
Public DomainDante Alighieri - Credit: Agnolo Bronzino

This is a reference to the Inferno, the first part of Dante Alighieri's 14th century epic poem, the Divine Comedy.

Dante is guided by the Roman poet Virgil through the nine circles of Hell, located deep within the bowels of the Earth.