Dublin Castle, the state governmental complex was originally built in the late XII and early XIII century as a defensive fortification after the vulnerable inhabitants of the city grew tired of repeated invasions by the Vikings and later, the Normans. It later became a royal residence and during this time and in following years many more buildings were added. It served as court until separate structures were eventually built for that purpose. In more recent times, as of 1930, the ceremony to inaugurate the Presidents of Ireland take place here and other diplomatic engagements are also held here. There are frequent concerts, and in May there is an Irish music festival worth watching.