The early 1200s were a hectic period in Dublin’s history. Almost every major landmark seems to have been built then. Dublin Castle was initially a traditional fortification consisting of a strong tower on an elevated point surrounded by a walled courtyard behind a protective ditch. Gradually, it became the residence and office of the Lord Lieutenant, who ruled Ireland as a representative of the English king. The castle stood next to a black pool (“Dubh Linn”), which gave the city its English name.