The Abandoned Ruins are actually embankment on the Wounded Coast leading into a since collapsed dwarven underground passageway from which the area takes its name. It is only accessible during Magistrate's Orders.
After agreeing to find an escaped criminal for Magistrate Vanard, Hawke travels to these ruins. An elven merchant, Elren, believes the criminal has taken his daughter into the caves and killed her. He complains to the guardsmen present about what he perceives to be injustice and inequality for the elves of Kirkwall. The guardsmen have been unable to capture the criminal, who turns out to be a killer who preys on elven children. Elren asks Hawke to find and kill the criminal.