The political state of Ireland in the 12th century, which led to the invasion of the Normans.

The expansion of the Norman castle building throughout the 13th and 14th centuries.

The haunted castle in Leap; the first castle to be besieged by cannon fire in Maynooth; love story of Dunluce and Clonony Castle.

Strategic military castles in Limerick, Birr, Kilkenny and Athlone; ruins of Aughrim Castle, the site where the bloodiest battle on Irish soil took place.

Gothic castles include Dublin Castle, Tullynally Castle and Birr Castle -- home of one of the largest telescope in the world; Charleville Castle undergoes re-building with the help of international volunteers.

The state of Ireland and its castles during the 19th and 20th centuries, including the personal, military, social and family stories behind the buildings.