The new runway at Dublin Airport will open just after 12 noon today.
3.1 kilometres long and costing 320 million Euro, it has taken six years to build but was delivered on schedule and within budget.
The new runway is expected to help expand passenger numbers beyond the 30 million that currently use the airport annually.
Graeme McQueen of the Dublin Airport Authority, says the new facility will assist greatly in growing the Irish economy.
"We can add more flights, more destinations and it makes us more appealing as a destination.
"We're fighting on a daily basis with airports all around the world to bring routes and services into Dublin and Ireland.
"It's an exciting day for Dublin Airport and an exciting day for Ireland as well."
But not everyone is happy about the new runway.
Michael O'Rourke is from St Margaret's The Ward Resident's Association and says night flights will cause havoc for his area.
"We welcome the opening of the runway and it's going to bring benefits not only to Fingal but to the country as a whole.
"Our problem is the removal of Condition 5 which restricted night flights.
That has been replaced by what they call a quota system which will allow them to fly through the night."