Vision of a Sunday morning

Several weeks ago, at about 9am on a Sunday I started hearing drums of war outside. I assumed they came from the nearby stadium past the Liffey which has always been a source of a variety of weird sounds.

I tried to stop thinking about it for some time even though not even my noise canceling headphones could cancel that noise. Eventually I left my flat to do some errands and when I arrived to the grand canal area this is what I saw:

No explanation came to mind and neither did the idea of asking them what they were doing.