Mouth of truth

Was originally used as a manhole that channeled excess waters off the streets into the Roman pipes. Over time it was believed that it was the mouth of the Oracles that spoke only truth and was often used as a tool to judge criminal trials, if the truth was not spoken then the Gods would cut off your hand!  It was even believed that the devil himself held the hand of the Emperor Julian inside his mouth so that he would not bring the Roman divinities back to life.  Which legend would you like to believe?