The chapter summarizes the nineteenth and twentieth centuries characterised by the proliferation of archival institutions, the appearance of purpose-built buildings. It characterizes the development of specialised services and enormous increase in user numbers. Starting in the 1960s and 1970s, archives buildings integrated new principles into the existing model. The creation of the European Union, a number of its constituent or associated bodies established their own archive services: these include the European Parliament in Luxembourg in 1974, the Council of Europe in 1952, originally also in Luxembourg before moving to Brussels, and the European Commission in Brussels in 1952. Perhaps most notably, the Historical Archives of the European Union at the European University Institute of Florence, opened in 1986, holds the archives not only of many community institutions but of the other organisations with pan-European interests and of private individuals.