Spanish architecture refers to architecture carried out in any area in what is now modern-day Spain, and by Spanish architects worldwide. The term includes buildings within the current geographical limits of Spain before this name was given to those territories (whether they were called Iberia, Hispania, Al-Andalus or were formed of several Christian kingdoms). Due to its historical and geographical diversity, Spanish architecture has drawn from a host of influences.

Since the first known inhabitants in the Iberian peninsula, the Iberians around 4000 BCE and later on the Celtiberians, Iberian architecture started to take shape in parallel with other architectures around the Mediterranean and others from Northern Europe.

A real development came with the arrival of the Romans, who left behind some of their most outstanding monuments in Hispania. The arrival of the Visigoths brought about a profound decline in building techniques which was paralleled in the rest of the former Empire. The Moorish invasion in 711 CE lead to a radical change and for the following eight centuries there were great advances in culture, including architecture. For example, Córdoba was established as the cultural Capital of its time under the Muslim Umayyad dynasty. Simultaneously, the Christian kingdoms gradually emerged and developed their own styles, at first mostly isolated from European architectural influences, and later integrated into Romanesque and Gothic streams, they reached an extraordinary peak with numerous samples along the whole territory. The Mudéjar style, from the 12th to 17th centuries, was characterised by the blending of cultural European and Arabic influences.

Towards the end of the 15th century, and before influencing Latin America with its Colonial architecture, Spain itself experimented with Renaissance architecture, developed mostly by local architects. Spanish Baroque was distinguished by its exuberant Churrigueresque decoration, developing separately from later international influences. The Colonial style, which has lasted for centuries, still has a strong influence in Latin America. Neoclassicism reached its peak in the work of Juan de Villanueva and his disciples.

The 19th century had two faces: the engineering efforts to achieve a new language and bring about structural improvements using iron and glass as the main building materials, and the academic focus, firstly on revivals and eclecticism, and later on regionalism. The arrival of Modernism in the academic arena produced figures such as Gaudí and much of the architecture of the 20th century. The International style was led by groups like GATEPAC. Spain is currently experiencing a revolution in contemporary architecture and Spanish architects like Rafael Moneo, Santiago Calatrava, Ricardo Bofill as well as many others have gained worldwide renown.

Because of their artistic relevance, many architectural sites in Spain, and even portions of cities, have been designated World Heritage sites by UNESCO. Spain has the second highest number of World Heritage Sites in the world; only Italy has more. These are listed at List of World Heritage Sites in Europe: Spain.