Ildefons Cerdà i Sunyer, (Catalan pronunciation: [ild?'fons s??'ða]; Centelles, December 23, 1815 – Caldas de Besaya, August 21, 1876), also known as Ildefonso Cerdá y Suñer in Spanish, was the progressive Catalan Spanish urban planner who designed the 19th-century "extension" of Barcelona called the Eixample.
He was a founder of modern town planning who coined the new word “urbanization”.