A degree in civil engineering followed in 1885, at which time he was apprenticed to Bindon Blood Stoney, who was engaged in a project to widen and dredge the entrance to the Port of Dublin.

After he finished his training, Westropp became the assistant surveyor for County Meath, but soon abandoned his professional work to pursue his archaeological interests.

[4][5] While surveying the field monuments of County Clare, he became fascinated by the variety and descriptiveness of the folk tales he heard being recited by the locals.

Westropp also undertook research into the early history of Clare and Limerick (which the Normans called Thomond) and published his finding in three historical essays covering the years 1275–1287, 1287–1313 and 1313–1318, respectively.

He then focused on the palaces of early Killaloe, other prehistoric stone-forts and the 'peel towers'or tower houses, eventually publishing several articles about his findings.