High crosses, for those less familiar with them, are the tall free-standing stone crosses characteristic of early medieval Ireland, typically decorated with carved scriptural scenes or interlace patterns and often associated with monastic settlements. That Thomastown should have one is not entirely surprising, given the area's deep ecclesiastical roots, but the cross itself occupies a quiet place in the historical record, noticed rather than celebrated.

Thomastown was founded in the thirteenth century by Thomas FitzAnthony, a Welsh settler who gave the town his name and set about establishing the kind of urban infrastructure common to Anglo-Norman plantation towns, including walls, a market, and religious foundations. The presence of a high cross suggests an earlier sacred geography underlying the later medieval settlement, hinting that the site held significance before the Normans arrived and reorganised it. High crosses in such contexts often mark the boundaries of monastic enclosures or serve as focal points for assembly and liturgy, their carved surfaces functioning almost as stone sermons in an age when books were scarce and outdoor gatherings common.