The name 'Cork' derives from the Irish 'Corcach Mór Mumhan', which means the 'great marsh of Munster' and refers to the fact that the centre of Cork city is built on islands, surrounded by the River Lee, which were marshy and prone to episodes of flooding. The waterways between the islands were built over to form some of the main streets of present-day Cork. The oblong-like shape of the centre-city island, bounded by the north and south channels of the Lee gives Cork city much of its physical charm. The topography of the city centre inspired Spenser's lines :
"The spreading Lee, that like an island fayre
Encloseth Corke with his divided flood"
No evidence has been discovered of a prehistoric settlement in Cork city. The area around Cork harbour was inhabited in prehistoric times and some artefacts, including axeheads, have been discovered in the environs of the city from that period. The scholarly consensus, however, is that these do not constitute evidence of an actual settlement in the city.
Traditionally, Saint Finbarre or Bairre, has been credited with the foundation of the monastery of Cork. Little is known with certainty about Bairre, as the extant 'lives' were composed long after his death, reputedly in the seventh century, and these contain mythical and folkloric elements. Pádraig Ó Riain, an eminent historian of early Irish history, has argued persuasively that Saint Finbarre was not a historical personage, and that the name Finbarre is another name for Saint Finian of Moville whose cult spread south into Cork. Other historians, while acknowledging that the lives give us little factual information about Finbarre, believe that he may have been a historical figure. The lives appear to have been composed in the context of a power struggle between dioceses in the twelfth century. Whatever conclusions are reached about the historicity or otherwise of Saint Finbarre, his name has been given to many places and institutions within the city, most notably to the splendid St Fin Barre's Cathedral, which is built on part of the site of the early monastic foundation of Cork.
The monastery of Cork which was built on elevated ground on the south bank of the River Lee is the earliest human settlement in Cork for which we have incontrovertible evidence. The date of the foundation is unknown but historians think that it was founded in either the sixth or seventh century. The earliest mention of the monastery in the annals is for 682, when the death of Suibne, abbot of the monastery, was recorded. The location of the monastic settlement was on the area around the present-day site of Saint Fin Barre's Cathedral. Evidence from maps and other sources suggest that the approximate boundaries of the monastery would have been along Bishop Street, Gillabbey Street, and the area between Barrack Street and Dean Street.
The monastery was one of the best known Irish monasteries and there are numerous references to it in the annals. Many of these references are to attacks on the monastery by the Vikings. Little is known about the actual physical appearance of the monastery but it is likely to have borne a general resemblance to other Irish monasteries of the period.