The Fall of the House of Usher

The narrator observes a large fissure or crack in the front of the home that reached from the roof to the tarn (a small mountain lake).

Perhaps the eye of a scrutinising observer might have discovered a barely perceptible fissure, which, extending from the roof of the building in front, made its way down the wall in a zigzag direction, until it became lost in the sullen waters of the tarn.