Although the start of O’Reilly’s tattooing career remains a mystery, it is believed he studied under ‘Old Martin’ Hildebrandt before opening his own shop at #5 Chatham Square, and later moving to #11 Chatham Square in the Bowery section of New York.
The Bowery was an infamous area of squalid tenement buildings, underground gambling dens, saloons and brothels. It was in this notoriously bare knuckle environment that O’Reilly tattooed several circus attractions, including 12 tattooed ladies, and the world’s first electrically tattooed attractions: Tom Sidonia, George Karlavagn, and George Mellivan, who each went on to have exciting careers of their own.