Búnker de Areneburu Historical milestone · Berango, Bilbo Handia / Gran Bilbao, Bizkaia Image of Berango, not of the place itself. Fortification built between 1936 and 1937 during the Civil War, restored in 2012 and opened as a testament to the defenses of the so-called Cinturón de Hierro (Iron Ring). 1936-1937 (construcción); 2012 (restauración) Photo: User:Javierme Javier Mediavilla Ezquibela (CC BY 3.0) What to see and do in Berango