Answer:
Poe has provided a detailed description about the structure of the vault as it signifies both the physical decay and the decay of Usher's family. The description of the vault foreshadows the decay of the family.
Explanation:
"The Fall of the House of Usher" is a short story written by Edgar Allen Poe. The story is about the Usher's family.
The narrator describes the wall of Usher's house in details as it foreshadows the fall of Usher's house. Just as the vault of Usher's house is crampled and decayed, the Usher's family is crampled and decayed within.
Therefore, the detailed description of the vault also provides details about the Usher's.
