One hundred years ago, a complete census of Ireland was taken as part of a larger census of the UK. The information gathered included details on every person compiled by household and by house address. This data included the name, sex, age, religion, place of birth and relationship to others in the household. As it transpired, this was the last census of the population for the entire island; the next census took place in 1926 and was of the newly formed Irish Free State. The original forms, which consisted of individual records compiled into tables for each house address, were digitised recently by the National Archives of Ireland. This provided an opportunity to undertake a geographical study of the 1911 Census in its centenary year. This research uses the records available for inner city Dublin to describe its social and demographic make-up 100 years ago. The paper highlights the variations that existed within the urban core and identifies four distinct ‘Dublins’ that existed at the time.