The apparently oldest drawing showing the surrounding — one Mercator drawing shows just the monument — is Ortelius Vivianus 1584:
We then get another take on it in Braun & Hogenberg: "Civitates orbis terrarum, III.", 1588:
(version from 1596)
Then the Blaeu in question in „theatrum urbium Belgicae“ shows us this in 1649:
(click for large)
We all know the impossiblity of proving a negative, but I'm going to go out on a limb and claim that there was no such ruin, and that the artist added it for symmetry or effect.
First, while there has been plenty written about the Säule and the Kirche, what I have read about the town of Igel did not reveal any other historic tower having been there. ...