FindMyPast has uploaded two sets of detailed old maps to its Irish collection, one created during the 19th century, the other from the late 16th:
Dublin City Ordnance Survey Map 1847
Covering Dublin at the height of the Great Famine, this is a large government map of the capital showing the location of streets, buildings, gardens, barracks, hospitals, churches and other landmarks. It has been captured in 33 sheets; if you follow the link above and scroll down, you'll find lists of all the wards and parishes covered.
Ireland, Maps and Surveys 1558-1610
This record set comprises 68 beautiful early Irish maps digitised in full colour from The National Archives (Kew) series 'State Papers Ireland'. These maps were created during the reigns of Elizabeth I and James I and were used by the English monarchy to confiscate land that had belonged to Gaelic leaders and redistribute them to English planters and settlers.