The paper explores processes of transnational network building in Europe in the 19th and 20th centuries. The first section reviews several relevant literatures. It concludes that historiographies of Europe often recognize the pivotal importance of transnational network building, but fail to analyse network developments as well as their entanglement with wider historical processes. Specialized infrastructure studies exist in economic and technological history, but have a distinct (sub)national focus. The networking of Europe has not been investigated. The second section presents a preliminary narrative of transnational network building in the 19th and 20th century. It highlights the relationship between network building and political events in different eras, as well as different types of ambiguities or tensions. The conclusion suggests a number of topics for further research.