Taoiseach Mr Ahern and former senator George Mitchell are expected to attend the event in Dublin Castle.

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Members of the public are advised to enter the security gates at the intersection of Parliament Street and Dame Street in front of Dublin Castle.

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Immediately after Michael D Higgins was declared president at Dublin Castle, I asked Mr McGuinness if he would meet the Queen in his capacity as deputy first minister.

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In the past decade, several Viking graves from pagan warrior burials have been unearthed south of Dublin Castle on Ship Street Little, South Great Georges Street and Golden Lane.

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Much of Dublin's early history is as murky as the peaty basin where the River Liffey joined the now-underground River Poddle, near the site of what is today the Dublin Castle gardens.

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Friday morning's proceedings inside Dublin Castle were intensely detailed and dry in tone, but there was enough interest from the public for a queue to form for seats in the small gallery.

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