The Legendary Fire is an event that was mentioned in Professor Layton vs. Phoenix Wright: Ace Attorney.
Long ago, the Great Witch Bezella supposedly used her magic to burn up the city. It is never mentioned why she would have done this. The event was very tragic and killed every person in the town aside from Espella Cantabella and Eve Belduke, who were on the Bell Tower. Arthur Cantabella and Sir Newton Belduke, who were exploring the ruins at the time, were also spared.
The event was actually caused by the ringing of the Bell of Ruin, which - due to being made out of pure silver - made all people in the city faint, allowing for a fire to spread with nobody to stop it.