The oldest architectural works in Spain date back to the megalithic culture, approximately 3000 BC. n. and. From this period until the Romanization of the Iberian Peninsula we are going to find very interesting finds and settlements of what has been generically called the Iberian or Iberian civilization. However, these are probably not the architectural monuments that one knows best in Spain, so a deepening in this sense could lead the visitor to find real surprises in various regions of the peninsula, especially in the Levantine area and to the south, in what refers to Iberians, and to the north, referring to Celtic or Nordic peoples in general.
- Institute of Cultural Heritage of Spain 
- National Library of Spain 
Not so recent times, such as the Roman, are monuments in the country, the most important being the colossal Aqueduct of Segovia and the Roman ruins of Mérida.
But perhaps what has really surprised the visitor for decades is what the Muslim era has left as an inheritance.
The great mosque of Córdoba is one of the most admired monuments, the other is, of course, the Alhambra in Granada, a surprisingly well-preserved palace in its original state.
The Alhambra Palace, in Granada, was the residence of the kings of Granada and is one of the most important exponents of ” Moorish ” architecture in Spain and one of the national treasures of that nation.
When we talk about Moorish, Arab, or Muslim Spain, we are talking about a particularity in the history of European art that can be confusing. For while Europe continues in feudal times, after the fall of the Roman Empire, to evolve in its Visigothic and later Romanesque and Gothic lines, as a country located in Europe according to THESCIENCETUTOR, Spain enters this chapter of history with an African invasion that, from the south, reaches almost all the peninsula.
Only to the north would some independent redoubts or kingdoms be preserved, which they would continue to build in a medieval European style and which would successively try for centuries to reconquer the territory towards the south. These would consequently carry this medieval European influence to territories that for a short or long period of time had been under Muslim influence in their customs and in their art.
On the other hand, when the Moors arrived in the Iberian Peninsula, their style was distinctly African, but after 800 years settled in it, logically they gradually became Hispanic, moving away from the African trends that centuries ago they would have brought with them. They then created a sui generis style, not without important technical and stylistic novelties that differed, centuries later, from what was built in Africa. This own style reaches its culminating point in the Caliphate style, generated in Córdoba, and whose maximum exponent was the Mosque.
These 800 years of history would be characterized by a very mestizo Spain, in which three populations with different religions, Jews, Muslims and Christians, would coexist in peace. As in Muslim territory, freedom of religion was respected, by which Jews and Christians could continue to live in peace and according to their customs, in the reconquered territories, until the time of the Catholic Monarchs, Muslims and Jews would also be allowed continue to live according to their traditions in reconquered territory. It is precisely this characteristic that creates this curious fusion of styles so characteristically Hispanic, where we see monuments of Mozarabic, Mudejar, and all possible combinations (Gothic-Mudejar, Romanesque with Mozarabic ornaments, etc.)
The word Mozarabic comes from the Arabic mustab ‘rab, which means that he wants to look like an Arab, and that is how the Christians who remained in conquered territory remained faithful to their religion. Its architectural style was called thus by extension, and was characterized by the use of essentially Visigothic construction techniques, modified by the caliphal influence.
On the other hand, the word Mudejar comes from the Arabic mudeyyen, which means those who are allowed to stay, they were Muslims who lived in Hispano-Christian territory. Again, its architectural style is called the same way, and it can be defined as that existing between the 11th and 15th centuries, in which Christian elements (Romanesque or Gothic) are mixed with Muslim structures, materials and decorative elements.
When Spain was still occupied by the Moors in the south, to the north Visigoth kingdoms coexisted, as has been said, those that for centuries would be engaged in the Reconquest of what had previously been Christian territory.
It is for this reason that in this area there are important architectural jewels of the Visigothic and Romanesque style. Exponents of this architectural style are found especially following the route of the Camino de Santiago, which would be established with great effort as a bulwark of Christianity.
In the 12th century, the Gothic style was introduced in Spain, reaching its maximum importance during the 13th century, when the Cathedral of Burgos, the Cathedral of Toledo and the Cathedral of León were built.
The arrival of the Renaissance in Spain is once again surrounded by Hispanic peculiarities. This time coincides with the end of the Reconquest, when the Catholic Monarchs take Granada, which was the last Muslim enclave, coincides, secondly, with the discovery of America and, thirdly, with the unification of Spain under the crown. of Castilla. This last aspect entails an intense effort on the part of the crown and the Catholic Church to use Christianity as a unifying element, thus ending the long tradition of religious freedom.
All these elements lead Spain to focus on the Renaissance also in a very sui generis way, and although it is also built in the purest Italian Renaissance style, we find a clearly Hispanic trend and much more ornamental than the Italian: The style Plateresque, name that designates the first Spanish Renaissance that includes the reigns of the Catholic Monarchs, Carlos V and Felipe II. The name comes from the similarity between the treatment of cut stone, in complicated and fine filigree, with that of silver in goldsmithing. One of the most representative monuments of this architectural style is the University of Salamanca.
The Cathedral of the Sagrada Familia in the city of Barcelona, work of the Catalan artist Antonio Gaudí and symbol of the architecture of Catalonia.
Baroque in Spain perhaps coincides with one of the most prolific and glorious eras of Spanish art. In architecture there are two very different visions that could be considered even contradictory: The Herrerian style, by Juan de Herrera, of great austerity, whose most representative exponent is the Monastery of El Escorial in Madrid, and the Churrigueresque style, named after the work of the Churriguera family, with ornate ornamentation and overflowing imagination, in which Spanish typicalism beats. Additionally, Galicia has an exceptional baroque boom, creating its own style, called Compostela Baroque, with Santiago de Compostela as its center.
Modernism in Spain again represents an important role within the international architectural context, with important architects, especially in Barcelona, who would go on to revolutionize traditional schemes.
The best known worldwide is perhaps Antoni Gaudí and his great cathedral the Sagrada Familia. But the evolutionary movement does not stop and, until today, Barcelona can be considered as an international center for the most innovative architecture.