The novel makes frequent references to "the liberties," a large area in the southwest part of central Dublin, and to streets in the area. In 1904 it was a blighted part of town whose tenement houses were crammed with the unemployed and destitute, prostitutes and criminals, middle-class citizens in danger of joining the underclass, and struggling immigrants.
The area got its name from the fact that lands that were eventually incorporated into the city began as the holdings of certain churches and aristocratic families, notably the Earls of Meath and the two cathedrals now known as Christ Church and St. Patrick's. English kings and courts granted exemption from city taxation and authorized the Liberties to establish their own courts and exercise economic powers. Freedom from municipal control enabled some of these areas to establish thriving textile manufacturing businesses in the 17th and 18th centuries. People who prospered in the weaving trade built many wealthy homes, as well as a weavers' guildhall. But various laws and economic forces conspired to destroy this prosperity by the end of the 18th century, and the 19th century saw uninterrupted decline. The wealthy houses were chopped up into apartments catering to the impoverished.
The detail from a 1798 map here (second illustration) shows several of the streets in the area that are mentioned in the novel. The Coombe, where the green and blue markings overlap (its name is unfortunately obscured by both these lines) runs east-west from Pimlico to Patrick Street. Due south of the eastern end of The Coombe is "Fumbailies La." ("Fumbally's Lane" in Aeolus), running east from the north end of Black Pitts. To the east of The Coombe, and just a little north, is St. Patrick's Cathedral, and to the east of that is Marsh's Library. Starting a little northeast of the cathedral, and running north, is Bride Street.