The name Dublin comes from the Gaelic dubh linn or “black pool” - where the Poddle stream met the River Liffey to form a deep pool at Dublin Castle. The city's modern name - Baile Áth Cliath – means the “town of the ford of the hurdles”. Ireland's four principal routeways converged at a crossing place made of hurdles of interwoven saplings straddling the low-tide Liffey.
837 AD – 917 AD: In 837, sixty Viking longships attacked churches round the Poddle and Liffey estuary, and the invaders made a permanent settlement in 841. 917 – 1014: Dublin was the Viking world’s largest city and traded from Iceland to Constantinople. The first genuine ruler of all Ireland - High King, Brian Boru - was rebelled against by Dublin Vikings and the Leinster Irish. With the aid of Vikings, Brian crushed his foes, then was himself slain, in an epic battle atClontarf in 1014. 1014 – 1170: The Vikings adopted Christianity and founded Christ Church Cathedral. In 1169, the deposed Irish King MacMurrough sought help from south-west Wales Normans who, under their leader Richard FitzGilbert de Clare (Strongbow), seized Dublin. 1171 – 1399: In 1171 Henry II landed with a great army, and made Dublin the capital of the Normans' Irish territory and the heart of the Norman and English colony. Christ Church was rebuilt in the Gothic style and work began on St Patrick’s Cathedral. In 1317 Scottish KingRobert the Bruce and brother Edward failed to take the city, but much destruction ensued. In1348 the city was gripped by the Black Death.