Officials at the French Interior Ministry say yesterday's rally in Paris was the largest demonstration in France's history.
Almost 2 million people lined the streets of the capital to show solidarity with the victims of last week's terror attacks that left 17 people dead.
Among the crowds was Taoiseach Enda Kenny who walked arm in arm with dozens of other world leaders.
Attention is now turning to international security, with the US holding a summit next month on how to fight violent extremism around the world.
Noel Canty is a reporter for French channel TV5 Monde - he says that French border control will almost certainly be tightened:
