Thanks for the replies, and your help, much appreciated. The best people to ask, I thought, are those living in Dublin!
I have questioned hubby again, his mother said it was a big, significant bridge, in Dublin, that he helped build, and his name was on the bridge. 1880's graffitti could well be the way his name was put on the bridge.
The only ancestor of my hubs that would have had anything to do with building bridges, would have been Edward Wild, as he seems to be the only stone preparer. Mother in law's only relations in Ireland were, John and Eliza O'Rourke (Eliza was Elizabeth Baxter before marriage) and of course any children they had, John was a bootmaker. These two were born in Dublin. Although the O'Rourke family were in England in 1881, they seemed to have moved back by 1901, as they are not on the census. Edward Wild married Mary Jane O'Rourke,(parents were John and Eliza), we presume in Ireland, as there seems to be no record of their marriage here.
I presumed it would have been a bridge over the Liffey. As this seems to be the main river in Dublin. My knowledge of Dublin is practically non-existant unfortunately. Are there any other large and 'significant' bridges in the Dublin area?
Again, thanks for the help