The Telefónica Building was officially opened in 1930 as part of the project to build the Gran Vía; back then it was Europe's tallest building, standing nearly 90 metres high, and its design was inspired by the skyscrapers of America.

It became the country's most important communications centre and a workplace for more than 1,800 employees, including the famous switchboard operators. The first transatlantic telephone call in Spain was made from here, connecting King Alfonso XIII with United States president Calvin Coolidge.

During the Spanish Civil War, the building's strategic position and impressive size made it both a target for enemy bombs and an air-raid shelter for the people of Madrid. It was also a working base for foreign correspondents covering the war, such as Ernest Hemingway and John Dos Passos, who sent their reports from here.

Nowadays, the Telefónica Building is home to the Espacio Fundación Telefónica, a centre for cultural activity and debate, hosting exhibitions, workshops and meetings, especially events focusing on cutting-edge art and technology.