What I find most interesting about this one is that I'm pretty sure it features in the British Pathé footage below from Queen Vic's visit. When I first saw this clip I racked my brains trying to figure out where it had been filmed, thinking it must be one of the gates of Phoenix Park. It was only when I read about the Royal Triumphal Archway of 1900 here that the penny dropped. Archiseek also contains information on other archways such as that for the royal visit of 1903, and the one constructed at Baggot Street for the royal visit of 1849.
Back in 1821, King George IV's visit to Dublin was celebrated in similar style as can be seen in these paintings by Joseph Patrick Haverty and William Turner de Londe respectively although we have a little mystery. I'm not sure why but the archways depicted differ quite a bit from one another, the first one looking decidely flimsier and less solid than the other one. They both appear to be in roughly the same place, where the Parnell Monument currently stands at the top of O'Connell Street. However the first picture might be depicting a different archway somewhere else in the city which would explain the discrepancy. But if it is the same spot in both pictures either one the paintings depicts a different occasion or one of the painters just didn't know what the archway looked like. Sadly no such structure was constructed for Queen Elizabeth II's much more recent visit to the fair city of Dublin.