The Big Picture One of the most beautiful and haunting moments of The Fall of the House of Usher takes place in Episode 7, "The Pit and the Pendulum" when Madeline Usher confronts Verna in the old Usher house. Verna recites a poem that speaks about death and the rise and fall of an eerie city, and, while indeed beautiful, does leave us scratching our heads at first.
There were multiple versions of "The City in the Sea" throughout the years, the original one coming out in 1831 with the name "The Doomed City", and being renamed "The City of Sin" in 1936 before getting its final title in 1849. The previous titles are possibly references to the biblical locations of Sodom and Gomorrah, cities that were destroyed by God due to their sins and morals that were contrary to those of the ancient Israelites.
In the final verses come the actual end of days, when "Hell, rising from a thousand thrones" comes to take everything down into the sea, while paying reverence to Death. The end comes slowly at first, but then the whole city is dragged down among waves that "have now a redder glow" and "amid no earthly moans." These last verses are especially interesting because they establish Death as being something worse than Hell itself, as the latter pays homage to the first.
The visual callback this scene makes to "The City in the Sea" is already striking, but Verna makes it even more so when she confronts Roderick. At first, it may seem like she has come for him this time, but she's actually there to explain to him why she killed all his children and is bringing down his empire, going back to the deal she struck with him and Madeline in 1979 on New Year's Eve.