Muse Lane was a horrific, over-crowded slum in the Cowcaddens. It was cleared around 1923 with most of the residents going to the new Hamiltonhill slum clearance housing scheme. Details in: Seán Damer (2018): "Scheming: A Social History of Glasgow Council Housing 1919-1956," Edinburgh University Press, Chapter 3, pp. 30-55. As many contributors have said, the Rat-Pit was a female lodging-house in Muse Lane graphically described in Patrick MacGill's novel "The Rat-Pit," first published in 1915, and republished subsequently several times.