Security forces are on high alert as the British Queen prepares for her historic four-day trip to Ireland.
A ring of steel has been erected around the capital after republican dissidents issued a bomb threat for central London on the eve of the trip.
Queen Elizabeth will make history when she arrives in Dublin and becomes the first monarch to visit the Republic, touching down at Casement Aerodrome at noon.
She will meet President Mary McAleese at her residence, Aras an Uachtarain, before one of the most significant engagements of her trip - a wreath-laying ceremony at the Garden of Remembrance, which honours those who died for Irish freedom.
But her momentous arrival is also shrouded with controversy and coincides with the 37th anniversary of the Dublin and Monaghan bombings, which killed 34 men, women and children.
Victim groups, which will hold a memorial for the dead in the morning, believe the bomb attacks were carried out by loyalist paramilitaries with British state collusion.
Armed British police officers will patrol the streets alongside thousands of gardai and soldiers to protect the 85-year-old monarch and the Duke of Edinburgh during the largest security operation in the history of the State.
Fianna Fail said the security threats in London were the actions of misguided criminals ignorant of the true values of republicanism.
Justice spokesman Dara Calleary said: "The message must go out loud and clear that the foolish actions of terrorists will not distract from what is an extremely positive and historic event in our country's history.
"The State visit of Queen Elizabeth this week further proves the success of the peace process and the determination of people across Ireland and Britain to move on from the oppression of the past."