Parts of the city have also been closed off.
Anti-austerity protests have taken place in Dublin City centre this afternoon with Dame Street, College Green, Molesworth Street and Kildare Street all closed off due as marchers taking part in the National Demonstration Against Austerity.
From the horde of original protesters, a small group of about seven to ten protesters managed to enter the premises in Bank of Ireland before Gardaí from the Public Order Unit arrived on scene to escort them away.
Here they are entering the building.
https://twitter.com/FINGALOLS/status/674238823774216193
It's believed that the 100 or so protesters on Dame Street were chanting "banks got bailed out, we got sold out! Developers got bailed out...." Here's some images of the protesters inside the building.

As you can see below, there was a considerable Gardai presence on the scene to escort them away.
https://twitter.com/FINGALOLS/status/674252754764865536
Images via - Carlow Water Metering/Water Privatisation Fight Back