In 1903, while living and working as a policeman in Chicago, Irish immigrant and traditional musician Francis O’Neill (1848-1936) published his first music collection entitled 'Music of Ireland', featuring over eighteen-hundred Irish traditional tunes largely sourced from fellow Irish immigrants settled in the Midwestern American ‘metropolis’ (Cronon 1991). O’Neill’s ‘Music of Ireland’ subsequently became a musical monument within an Ireland-centric historiography of Irish traditional music culture (Breathnach 1977; Ó Canainn 1993). O’Neill was lauded for having ‘saved’ (Carolan 1997) the predominantly nineteenth-century repertoire by harvesting it from the streets of Chicago and delivering it ‘home’ to its ‘authentic’ and original source. Building upon more recent critiques of O’Neill and his reception history (Bohlman 2004; Stokes and Bohlman 2003), this paper offers another perspective on 'Music of Ireland', focussing on O’Neill’s modernist urge to colonize and rationalize Irish music materials through the creation of a definitive, ‘biggest and best’ music publication to be disseminated not just to audiences located in Ireland but particularly to those located across North America and the global Celtic Diaspora. 'Music of Ireland' demonstrates a suppression of ‘porosity’ (Benjamin 1986) where a natural layering of history and social relations in music is replaced by a totalizing scheme inspired by the city in which O’Neill resided. From layout to typographic choices, O’Neill’s Chicago - as a particular expression of modernity, as an organizing principle, and as civilizing force - shaped the way in which musical knowledge was collected and arranged for redistribution.