Why did Montresor go to such lengths to get his revenge? After all, he could merely have run Fortunato through with his sword.
Perhaps the next-to-last sentence of Edgar Allan Poe's short story, "The Cask of Amontillado," answers this question best:
For the half of a century no mortal has disturbed them (the body).
Although running Fortunato through with a sword might have been a swifter solution, Montressor still had to get rid of the body. Rather than drag the bloody body into the catacombs, Montressor simply lured Fortunato to the exact spot that he wished him to finally rest. By chaining Fortunato to the wall, Montressor could work at his own pace without the worry of escape. It may have been a bit complicated, but it turned out to be a perfect crime.