King John's Castle

King's Island was a fortress long before the castle. In 922 the Viking sea-king Tomrair mac Ailchi built the first permanent Viking stronghold on Inis Sibhtonn, as the island was then known, and used it as a base to raid the length of the River Shannon from Lough Derg to Lough Ree, pillaging ecclesiastical settlements. The Limerick Vikings' power did not last: defeated by the Dublin Vikings on Lough Ree in 937, they were beaten again in 943 when the chief of the local Dalcassian clan joined forces with Ceallachán, king of Munster, and were reduced to paying tribute to the clans — a minor power thereafter, though one that often played its part in the endless struggles of the following centuries.

In 1174 Domnall Mór Ua Briain burned the settlement to the ground in a bid to keep it out of Anglo-Norman hands. It bought only two decades: after his death in 1194 the Anglo-Normans captured the area in 1195 under John, Lord of Ireland, and in 1197 Richard I of England gave Limerick its first charter and its first mayor, Adam Sarvant.

The castle that bears King John's name was built on his orders and completed around 1210, set on the boundary of the River Shannon to protect the city from the Gaelic kingdoms to the west and from any rebellion by Norman lords to the east and south. Under the general peace imposed by Norman rule, Limerick prospered as port and trading centre — helped by the castle acting as a watchdog on cargo passing through the port. The city split into "English Town" on King's Island and "Irish Town" on the south bank, and grew wealthy enough that King John set up a mint in the north-west corner of the castle; its pennies and halfpennies can be seen in Limerick museum today.

The wealth lasted. A document prepared for the Spanish ambassador in 1574 called Limerick "stronger and more beautiful than all the other cities of Ireland, well walled with stout walls of hewn marble", entered only by stone bridges of fourteen and eight arches; in 1620 the judge Luke Gernon found the marble high street "so magnificent that at my first entrance it did amaze me".

The castle endured five sieges during the 17th century, and the first left its walls severely damaged. In 1642 it was occupied by Protestants fleeing the Irish Rebellion of 1641 and besieged by an Irish Confederate force under Garret Barry. Barry had no siege artillery, so he undermined the castle walls by digging away their foundations. Those inside surrendered just before the walls came down — but the foundations were so badly damaged that a section of them had to be pulled down afterwards.

Archaeological excavations at the site in 1900 uncovered the remains of the Viking settlement. Some of the external walls, towers and fortifications still stand, and between 2011 and 2014 the castle underwent a €5.7 million redevelopment, gaining a new visitor centre and interactive exhibitions with computer-generated animations.