The whole complex, from a Spanish architecture stance, is one of the first examples of Modernismo [es][dubious – discuss] and most representative, to be built in the centre of Madrid,[3] with its Neoplateresque façade and Baroque Salamanca evocations.

[4] The building was designed by the young Spanish architects Antonio Palacios and Joaquín Otamendi through a municipal competition to be the headquarters for the Society of Post and Telegraph of Spain.

The decorative motifs of the façade and interior were made by the romantic sculptor Ángel García Díaz, a regular collaborator of Antonio Palacios.

After their construction and due to the wear and tear of normal use, the buildings slowly started to show signs of the modifications made, which included alterations to improve the communication systems.

The decline in the use of postal mail in the late twentieth century gradually reduced the functions of the complex, and, as a result, it began to lose its importance.

Madrid was growing in population and size in the seventeenth century after the decision of Philip II of Spain to transform the city onto an administrative and political centre for the nation.

Madrid's population growth meant that postal communication during the reign of Fernando VI of Spain was promoted through the construction of the Real Casa de Correos (Royal House of Letters), which was allocated to the Spanish architect Ventura Rodríguez.

The widening alterations to Puerta del Sol in 1856 led to the Casa de Correos finally hosting the Ministry of the Interior.

The preliminary draft was approved by the minister of Public Works, Claudio Moyano, for the expansion on 19 July 1860; following the proposal project of the architect and engineer Carlos María de Castro to expand the old city limits.

During Spain's restoration period, the Paseo del Prado and Recoletos continued being the preferred location for prestigious institutions and organisations, as well as mansions.

The construction started quickly and the people gave it the humorous name 'Nuestra Señora de las Comunicaciones' (Our Lady of Communications) because of its monumental character and size.

The media announced that Francos Rodríguez (as Director General of Communication) and Santiago Alba (as Minister of the Interior) were to visit the construction.

After twelve years of construction, the building was officially opened at midday on 14 March 1919, with the name 'Catedral de las Comunicaciones' (Cathedral of Communications).

The royal couple, Alfonso XIII and his wife Victoria Eugenie, attended the celebration accompanied by members of the government.

The palace was at the time a symbol of national progress, modernity and the ideas of regenerationism that were taking root in the media and in some of the intellectuals of the age.

In 1927 saw the construction of the rear half of the Bank of Spain (Banco de España), which is situated on Calle Alaclá, demolishing the Casas-Palacio (known as Santamarca) for its completion.

Despite the important location, the building did not suffer major damage from the bombings that devastated Madrid during the Spanish Civil War.

The bullet holes were caused by the military-like actions at the end of the Civil War (at the beginning of March 1939), as a consequence of Segismundo Casado's revolt against Juan Negerín's government.