 The alley is named after the defensive tower "Gråmunketornet" ("Greyfriar's Tower") located in the city wall which used to pass along the eastern side of today's Västerlånggatan.The tower was named after the Greyfriars abbey on Riddarholmen, which at the time was called "Gråmunkeholmen" ("Greyfriar's Islet").The alley appears in historical records as "grabroder strate" ("grey brother's street") in 1420 and "gramunka grendenne" ("[the] grey monk's alley") in 1456.