U.S. President Barack Obama (C) walks with Irish President Mary McAleese (R) at the Presidential Residence in Dublin May 23, 2011. Also in the picture are U.S. first lady Michelle Obama (2nd L) and McAleese’s husband Martin (L). Obama opened a four-nation tour of Europe on Monday in Ireland where he will explore his Irish roots in a town that was home to his great-great-great grandfather. REUTERS/Larry Downing (IRELAND – Tags: POLITICS)