Chillida's sculptures concentrated on the human form (mostly torsos and busts); his later works tended to be more massive and more abstract, and included many monumental public works.^[4] Chillida himself tended to reject the label of "abstract", preferring instead to call himself a "realist sculptor". Upon returning to the Basque Country in 1951, Chillida soon abandoned the plaster he used in his Paris works – a medium suited to his study of archaic figurative works in the Louvre.^[5] Living near Hernani, he began to work in forged iron with the help of the local blacksmith, and soon set up a forge in his studio. From 1954 until 1966, Chillida worked on a series entitled Anvil of Dreams, in which he used wood for the first time as a base from which the metal forms rise up in explosive rhythmic curves.^[6] He began to make sculpture in alabaster 1965.^[2] Rather than turn over a maquette of a sculpture to fabricators, as many modern artists do, Chillida worked closely with the men in the foundry. He then usually added an alloy that caused the metal to take on a brilliant rust color as it oxidizes.^[7]

From quite early on, Chillida's sculpture found public recognition, and, in 1954, he produced the four doors for the basilica of Arantzazu, where works by other leading Basque sculptors – Jorge Oteiza, Agustin Ibarrola and Nestor Basterretxea – were also being installed. The following year, he carved a stone monument to the discoverer of penicillin, Sir Alexander Fleming, for a park in San Sebastián (it subsequently disappeared, but a new version has been installed on the promenade at San Sebastián bay).^[4] By the early 1970s, his steel sculptures had been installed in front of the Unesco headquarters in Paris, the ThyssenKrupp building in Düsseldorf, and in a courtyard at the World Bank offices in Washington