The structure has four arches, but they are not evenly distributed: three round arches sit close together, while a fourth stands apart on the southern bank, as though added or altered at a different moment in the bridge's life. That asymmetry is not merely aesthetic. Look at the lower portions of the walls and the stonework visibly changes character, suggesting an earlier phase of construction that may date back to the medieval period.

The bridge takes its name from the Cardiff family, whose association with this crossing point along the Tolka gave the surrounding area its identity. The parapet walls are built of coursed limestone masonry, meaning the stone is laid in regular horizontal layers, with granite coping running along the top edge as a finishing course. It is this combination of materials and the shift in the quality and character of the lower stonework that led researchers Simington and O'Keefe, writing in 1991, to propose that parts of the structure belong to a considerably earlier building phase than the rest. The Tolka was historically a working river, and crossings along it had practical importance for movement between Dublin and the north of the county, making a medieval origin here quite plausible.

The bridge sits in an area that has been substantially absorbed into suburban north Dublin, and it can take a moment to locate amid the surrounding streets. It spans the Tolka south of the old village core of Finglas, and approaching on foot along the river bank gives the clearest sense of the structure's proportions. The variation in the stonework is most legible from below the parapet level, where the change in texture and coursing becomes apparent to anyone who knows to look for it. There is no formal heritage marker here, so the bridge tends to pass unremarked by those who cross it daily.