title: Dublin
context: It is now thought[24] the Viking settlement of about 841 was preceded by a Christian ecclesiastical settlement known as Duibhlinn, from which Dyflin took its name. Beginning in the 9th and 10th century, there were two settlements which later became the modern Dublin. The subsequent Scandinavian settlement centred on the River Poddle, a tributary of the Liffey in an area now known as Wood Quay. The Dubhlinn was a pool on the lowest stretch of the Poddle, used to moor ships. This pool was finally fully infilled during the early 18th century, as the city grew. The Dubhlinn lay where the Castle Garden is now located, opposite the Chester Beatty Library within Dublin Castle. Táin Bó Cuailgne ("The Cattle Raid of Cooley") refers to Dublind rissa ratter Áth Cliath, meaning "Dublin, which is called Ath Cliath".
question: When was Dublin founded?
answers: 841