The varnish layer of the work, which is held in Berlin's Gemäldegalerie, is degrading the tempera paint

Made in a Florentine workshop set up by Duke Cosimo I de’ Medici, Minneapolis Institute of Art’s Renaissance tapestry depicts Dante meeting Virgil in Hell

The space, which was discovered in a former coal bunker accessed via a trapdoor, features never-before-seen drawings by the Renaissance master