The one with the canal... The adjacent building reminds me of a Modern church we used to go to an odd time which was near the botanical gardens. We probably went to Sunday Mass there if we were going to the botanical gardens later. I don't remember the canal being that close though.
It's not a canal, it's the river Tolka. The nearby building is indeed Our Lady of Dolours, where I've often attended Mass, including Irish language Mass.
That could be it then. One thing I always remember about that particular church is receiving Communion from a special-minister for the first time. I'd never seen anyone, besides a priest distribute Communion before. Even though she was a religious, dressed in veil,I still struck me as extremely odd at the time( was probably shortly after my First Communion) It wouldn't have happened at St Peter's back then as there were heaps of Vincentian fathers in residence to assist.