Irun, city, Guipúzcoa provincia (province), in the Basque Country comunidad autónoma (autonomous community), northern Spain. It is situated on the left bank of the Bidasoa River. At Irun the river is bridged to Hendaye, France. Irun is the northern terminus of the Spanish Northern Railway and is the most important customs station for Spanish overland trade with the rest of Europe. The city has ironworks, tanneries, potteries, and paper mills. A dependency of neighbouring Fuenterrabía until 1766, Irun became a city in 1913. It underwent heavy siege by Nationalist forces during the Spanish Civil War, capitulating after fierce resistance in September 1936. Pop. (2007 est.) mun., 60,416.