Sligo (ˈslaɪɡoʊ ; Sligeach ˈʃljɪɟəx, meaning 'abounding in shells') is a coastal seaport and the county town of County Sligo, Ireland, within the western province of Connacht. With a population of approximately 20,000 in 2016, it is the largest urban centre in the county, with Sligo Borough District constituting 61% (38,581) of the county's population of 63,000. Sligo is a commercial and cultural centre situated on the west coast of Ireland. Its surrounding coast and countryside, as well as its connections to the poet W. B. Yeats, have made it a tourist destination. History of Sligo Sligo is the anglicisation of the Irish name Sligeach, meaning "abounding in shells" or "shelly place". It refers to the abundance of shellfish found in the river and its estuary, and from the extensive shell middens in the vicinity. The river now known as the Garavogue (An Ghairbhe-og), perhaps meaning "little torrent", was originally called the Sligeach. It is listed as one of the seven "royal rivers" of Ireland in the ninth century AD tale The Destruction of Da Dergas Hostel. The river Slicech is also referenced in the Annals of Ulster in 1188. The Ordnance Survey letters of 1836 state that "cart loads of shells were found underground in many places within the town where houses now stand". The whole area, from the river estuary at Sligo, around the coast to the river at Ballysadare Bay, is rich in marine resources which were utilised as far back as the Mesolithic period. The importance of Sligo's location in prehistory is demonstrated by the abundance of ancient sites close by and even within the town. For example, Sligo town's first roundabout was constructed around a megalithic passage tomb at Abbeyquarter North in Garavogue Villas. This is an outlier of the large group of monuments at Carrowmore on the Cúil Iorra Peninsula on the western outskirts of the town. The area around Sligo town has one of the highest densities of prehistoric archaeological sites in Ireland, and is the only place in which all classes of Irish megalithic monuments are to be found together.