The themes of The Fall of the House of Usher are the typical representative themes of Romanticism and 19th century Gothic literature. They include:
1. The inevitability of death
2. The authority of fate vs. our own free will
3. Nostalgia and sadness for better times gone by.
4. Inevitability of disgrace (as if destiny had precluded the characters to settle for it)
5. Darkness as a foreshadowing of the end, and as an atmospheric stylistic device.
** All these are staple themes of Romantic Gothic Literature which permeate through all of Poe's major works just like the works of his peers at the time.