Joe Biden was greeted by the Irish deputy premier Micheal Martin as he toured Carlingford Castle in Co Louth in the first official visit of his Irish trip.
The US president has embarked on a four-day tour of the island of Ireland to mark the 25th anniversary of the Good Friday Agreement - the peace deal that largely ended the Troubles in Northern Ireland.
Co Louth was home to Mr Biden's ancestors on his mother's side in the 1800s.
