Dublin Castle Ireland (1800–1922). After the signing of the Anglo-Irish Treaty in December 1921, the complex was ceremonially handed over to the newly formed Provisional Government led by Michael Collins. It now hosts the inauguration of each President of Ireland, and various State receptions. The castle was built by the dark pool ("Dubh Linn") which gave Dublin its name. This pool lies on the lower course of the River Poddle before its confluence with the River Liffey; when the castle was built, the Liffey was much wider, and the castle was effectively defended by both rivers. The Poddle today runs under the
Roads in Ireland that time, Ireland's main cities (Cork, Limerick, Galway, Waterford and Belfast) excluding Derry were connected to Dublin with motorways or with near-motorway standard roads. Dublin was the focus of some other major projects, such as the East-Link and West-Link toll-bridges, as well as the Dublin Port Tunnel. Major by-pass projects were also built around other cities and towns. The Jack Lynch Tunnel under the River Lee in Cork was a major project outside Dublin, and a fourth crossing at Limerick under the River Shannon (known as the Limerick Tunnel) opened in 2010. The different classes of roads in Ireland are