Missing two structures north/south of here; local knowledge needed
See Geograph linked at the bottom for more details
May sometimes be underwater.
Not visible on Esri Clarity, nor British War Office layer.

Suggested tags:

wikimedia_commons=File:The Duck Pond, Kilkenny Castle grounds - geograph.org.uk - 3361068.jpg

Sources

Aerials are regular Esri, Maxar Premium, Bing, Mapbox

Mapillary

There are plenty of pictures from around this pond. They're especially visible on the 360 ones of course. See e.g.
https://www.mapillary.com/app/?pKey=5467349640005322&focus=photo

Wikimedia Commons

Similar image to the Mapillary example linked above, but from the other side of the pond.

https://commons.wikimedia.org/wiki/File:The_Duck_Pond,_Kilkenny_Castle_grounds_-_geograph.org.uk_-_3361068.jpg

Geograph (use for reference only!)

The other Geograph image seems not to be on Commons as far as I can see. This one has more details however:

https://www.geograph.ie/photo/6625167