South Dublin South Dublin South Dublin () is a county in Ireland, within the province of Leinster, and the Dublin Region, a successor to County Dublin, from which its name derives. South Dublin County Council is the local authority for the county. The county contains both dense suburbs of Dublin and stretches of unpopulated mountain. In 2011 it had a population of 278,749, making it the third most populous county in the state. South Dublin has an area of 222.74 square kilometres. It is bounded by Dublin City (15 km to the north east), the River Liffey (separating it from Fingal to
Belfast–Dublin line Belfast–Dublin line The Belfast–Dublin line is a main and busiest railway route on the island of Ireland that connects Dublin Connolly station in the Republic of Ireland and station in Northern Ireland. The railway line was built by three separate companies. In 1837 the Ulster Railway began building a railway line between Belfast and Lisburn, which was extended in stages to Portadown in 1842 and as far as Clones by 1863. The Dublin and Drogheda Railway (D&D) built the line between Dublin and Drogheda. The Dublin and Belfast Junction Railway (D&B Jct) linked the Dublin and Drogheda with the Ulster