Waterford Walls is a street art festival that has been taking place every year in Ireland since 2015. there are still one or two that i havent found yet but ive got most of them mapped out at this stage so it should make it easier for others to find them, especially the ones that are off the beaten track. here are some Overpass turbo queries that show where they are:

https://overpass-turbo.eu/s/JRF (2018 walls are shown in blue)
https://overpass-turbo.eu/s/JRD (same search but with artist names and years displayed)

or you can use OsmAnd on Android (Play Store, F-Droid) or iPhone (App Store)

- search for “mural”
- select “Artwork type: mural” in the search results
- select “Show artwork on the map”

tap on a marker and drag the window up to view more details. if you have an internet connection then scroll to the end and tap on “online photos” to view any nearby street-view images that might be on Mapillary