Repair work has started at Cook Street in Dublin on one of the remaining sections of the old city wall. Built around 1100 it marked a significant development in the city’s defences. Under the rule of Irish king Muirchertach Ua Briain, the earthen banks were replaced by a robust stone wall. Made of local limestone, it was about seven metres high and three metres wide. It incorporated at least three documented gates: St Mary’s Gate to the east, St Nicholas’s Gate to the south and the western gate. It is speculated that it probably included access to the River Liffey on the northern side. Significant portions of the wall remain today, particularly at Cook Street and beneath the Dublin Civic Offices. In periods after its construction, such as the Anglo-Norman invasions of the late 12th century, the walls were tested and further strengthened. This period into the early 13th century also saw the construction of Dublin Castle, which was considered a key fortification. Further defensive expansions were added after the construction of the castle, including a northern extension wall toward the Liffey, reflecting the city’s growing need for protection. Excavations at various sites, including Wood Quay and Bridge Street, have revealed remnants of extensive fortifications. A team of conservation experts has been appointed to carry out repairs. The works include repointing and replacing missing capping stones, graffiti removal, as well as repair and painting of St Audoen’s Gate. There are further plans to conserve Dublin’s medieval history. DCC recently appointed an integrated design team to undertake a structural and condition survey of another section of the city wall at Ship Street. They will develop proposals to conserve the wall at Ship Street within a new public space and seek to create links with other parts of the ancient fortification circuit, including Dublin Castle.