Tourism in the Republic of Ireland on were built by them. As Dublin Airport is located just outside the city, most international visitors to Ireland begin their stay here. Among the main attractions in Dublin are Dublin Castle, the seat of British rule in Ireland until 1922, Phoenix Park, one of the largest inner city parks in the world, The General Post Office, one of Ireland's most famous buildings due to the 1916 Easter rising, Kilmainham Gaol, a former prison turned museum that held and executed the rebels of the 1916 Rising and Trinity College, where the Book of Kells and the Book of Durrow are
Karl Radek Left, with which he had close links from his time in Germany, introducing him to Paul Levi at this time. He took part in the Zimmerwald Conference in 1915, siding with the left. During World War One, Radek engaged in polemics with Vladimir Lenin over the subject of the Irish Easter Rising of 1916; while Lenin was strongly enthusiastic about the Rising, seeing it as a blow to English imperialism, Radek disagreed. Basing his view on Theodore Rothstein (a Jewish emigre from the Russian Empire, living in London), he claimed that, what he called the "Sinn Féin movement" was petit-bourgeois