At Baldongan in County Dublin, there is nothing left to see. A set of fish ponds once occupied a break in the slope at the bottom of a field, and they have since been filled in so completely that no surface trace remains. The site is, in practical terms, invisible, which makes the documentary record of it all the more curious.

The ponds were described by Austin Cooper in 1783, a period when antiquarian travellers were beginning to record the Irish countryside with some methodical care. Cooper's account was later cited in a 1914 publication, and it represents almost everything that is now known about the feature. Fish ponds of this kind were typically a medieval or early post-medieval amenity, maintained by monastic houses, manorial estates, or wealthy households to keep a supply of fresh fish, particularly on days when meat was restricted by religious custom. They were usually engineered into the landscape rather than dug flat, taking advantage of natural water movement, which would explain why these particular ponds were positioned at a topographical break of slope, where drainage from higher ground could be channelled and retained. Whether any structure of that kind existed at Baldongan, and who maintained it, the surviving notes do not say.

For anyone visiting the Baldongan area, which is most often explored in connection with the nearby ruined castle and church, the fish pond site offers nothing to observe directly. The relevant field has been altered over time, and no earthwork or depression has been recorded as remaining. The value of knowing about it lies more in the landscape reading it encourages: the habit of looking at a slight change in gradient and considering what past use it might once have served. Cooper noted it, someone thought it worth preserving in print in 1914, and the record has been maintained since, even as the physical evidence disappeared altogether.