Using a diverse range of source material this paper highlights the colonial appropriation of the existing Gaelic market town of Cavan, founded by the O'Reillys, in the establishment of the first Ulster plantation town. In contrast to what may be expected, a reading of the socio-economic, political and cultural landscape of the newly incorporated town of Cavan in the early years of the 17th century, highlights the dominant position and important civic role played by families of Gaelic origins in the governance of the town. Unlike other plantation towns Cavan town remained 'unplanned' in its morphological layout with the colonisers utilising and modifying the existing Gaelic urban fabric. The decision by English colonial powers to use the pre-existing urban settlement of Cavan town led to success for the colonial project on paper. Unlike other Ulster plantation towns, it also uniquely permitted the retention of a strong and distinct Gaelic presence and character which manifested itself in both the population and space of the town during the early decades of the 17th century