Ildefons Cerdà i Sunyer (Catalan pronunciation: [ild?'fons s??'ða i su'?e]; Spanish: Ildefonso Cerdá Suñer; 23 December 1815, Centelles – 21 August 1876, Caldas de Besaya) was a Spanish urban planner and engineer who designed the 19th-century extension of Barcelona called the Eixample.