They are headed for the brand new Aviva stadium on the south side of the River Liffey.
In many cities the size of Dublin, an amphitheatre like the Aviva would be the premier sporting venue.
But not here. On the other side of the river, the fourth largest stadium in Europe rises high over winding working class streets.
Croke Park does not seem a familiar name to the Portuguese visitors. One after another shook their head when asked if they knew of it.
That is not really surprising. For most of its history, Croke Park has been Ireland's secret jewel.
Its owners, the Gaelic Athletic Association (GAA), guarded it closely from what it called "foreign games", insisting that only gaelic football and hurling should be played there.
Its specifications were only very occasionally relaxed - a Muhammad Ali boxing match took place there in 1972.
One rule which did remain in place though was that anyone who has any association with the British state was explicitly banned from being a member.
American boxers were one thing - police officers from Northern Ireland another.
The GAA's resolution was fortified by its collective memory of Bloody Sunday in 1920 when British troops, responding to IRA attacks earlier in the day, fired on crowds gathered at Croke Park to watch a match.
Among the 14 killed was the captain of the Tipperary team, Michael Hogan.
For many decades afterwards, the idea that a British monarch would one day be welcomed to Croke Park, would have provoked anger within many in the GAA.
Now, it has happened, and the mood of the majority of Dubliners is anything but fury.
As the Queen smiled with the GAA president alongside the hallowed turf, people outside were similarly relaxed.
O'Shea's Pub in nearby Gardiner Street is decorated with the flags of many of the Irish county teams.
It's a popular haunt for those seeking a quick pint before or after a big match.
On Wednesday, people gathered outside it waiting for the Queen to pass and yet another security cordon to be lifted.
One said that she had enjoyed watching the television pictures of the state visit the previous evening.
"She is just like a little old lady - like your granny," she said.
"I hope I look as well as she does when I'm her age."
A few yards away at the barrier, some people were becoming frustrated at waiting for it to be lifted.
One fruitlessly argued with a police officer that getting to the bank by half past four qualified as an emergency.
The street merchants took advantage of the assembled crowds, showing off their football-related wares.
Their most popular item in the last couple of days has been a scarf half blue and half red, sharing the colours of opponents Porto and Braga.
It suggests there is not much enmity between these two Portuguese teams.
In a city where reconciliation is the theme this week, it seemed appropriate.
From a distance, it sounded like the shouts of protesters but turned out to be the songs of some of the thousands of Portuguese football supporters in the city for a European final.