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
Transport in Dublin section, and four lanes each way between junctions on the Northern and Western sections. Transport Infrastructure Ireland also increased capacity at many of the motorway's busiest junctions by building triple-grade interchanges instead of the lower capacity roundabouts and crossroads that had been in place. The toll at the West-Link which caused huge tailbacks was demolished and replaced by a tag tolling system. This reduced tailbacks greatly. The M1, M2, M3, M4, M6, M7, M8, M9 and M11 motorways all serve the Greater Dublin Area. Dublin is surrounded by what have been termed by Dublin City Council as an inner and