Notable Portuguese architects of the past have included Diogo de Arruda (15–16th c.), João Antunes (17th c.), Eugénio dos Santos and Carlos Mardel (18th c.), José Luis Monteiro (19th c.), Raul Lino, Cassiano Branco and Fernando Távora (20th c.).

Celtic pre-historic fortified villages dating from the Chalcolithic are found along the Tagus river like that of Vila Nova de São Pedro, near Cartaxo, and the Castro of Zambujal, near Torres Vedras.

This region was dotted with hillfort villages (called citânias or cividades) that for the most part continued to exist under Roman domination, when the area became incorporated into the province of Gallaecia.

The houses inside the castros are about 3.5 to 5 meters long, mostly circular with some rectangular, stone-made and with thatch roofs which rested on a wood column in the centre of the building.

The excavations revealed city walls, baths, the forum, an aqueduct, an amphitheatre, and houses for the middle classes (insulae), as well as luxurious mansions (domus) with central courtyards decorated with mosaics.

Built between the 8th and 13th centuries, Silves Castle has preserved its walls and square-shaped towers from the Moorish period, as well as 11th-century cisterns – water reservoirs used in case of a siege.

Despite the changes, the original labyrinthic interior with its "forest" of pillars, three horseshoe arches with an alfiz the inner wall with a decorated niche, a mihrab pointing to Mecca, all show the same contemporary Islamic features found in Spain and the Maghreb.

In Coimbra, Afonso Henriques created the Santa Cruz Monastery, one of the most important of the monastic foundations of the time, although the current building is the result of a 16th-century remodelling.

The church is a round structure with a central arched octagon, and was probably modelled after the Dome of the Rock in Jerusalem, which was mistakenly believed by the crusaders to be a remnant of the Temple of Solomon.

The first fully Gothic building in Portugal is the church of the Monastery of Alcobaça, a magnificent example of the clear and simple architectural forms favoured by the Cistercians.

The apse of Lisbon Cathedral was totally remodelled in the first half of the 14th century, when it gained a Gothic ambulatory illuminated by a clerestory (high row of windows on the upper storey).

Several Gothic cloisters were built and can still be found in the Cathedrals of Oporto, Lisbon and Évora (all from the 14th century) as well as in monasteries like Alcobaça, Santo Tirso and the Convent of the Order of Christ.

In the Alentejo, Mudéjar influence in several buildings is evident in the profile of windows and portals, often with horseshoe arches and a mullion, circular turrets with conical pinnacles, Islamic merlons etc., as well as tile (azulejo) decoration.

The construction of churches and monasteries in Manueline, especially in Lioz, or royal stone, was largely financed by proceeds of the lucrative spice trade with Africa and India.

The painter and architect Francisco de Holanda, writer of the book Diálogos da Pintura Antiga ("Dialogues on Ancient Painting"), disseminated in this treatise the fundamentals of this new style.

However, the best known Portuguese architect in this period was Afonso Álvares, whose works include the cathedrals of Leiria (1551–1574), Portalegre (begun 1556), and the Church of São Roque in Lisbon.

In his wake came several Portuguese architects: During the union of Portugal and Spain, the period between 1580 and 1640, a new style developed called "Arquitecture chã" (plain architecture) by George Kubler.

[1] Basically mannerist, this style also marked by a clear structure, a sturdy appearance with smooth, flat surfaces and a moderate arrangement of space, lacking excessive decorations.

When king Filipe II made his Joyous Entry in Lisbon in 1619, several temporary triumphal arches were erected in the Flemish style of Hans Vredeman de Vries.

The Águas Livres Aqueduct brings water to Lisbon covering a distance of 11.18 miles, with emphasis on the section over the Alcântara valley because of the monumentality of the imposing arches.

This monumental palace-monastery-church complex is even larger than the El Escorial, an immense 16th-century Spanish royal palace north of Madrid to emphasize the symbolic affirmation of his power.

The sanctuary Bom Jesus do Monte near Braga, built by the architect Carlos Luis Ferreira Amarante is a notable example of a pilgrimage site with a monumental, cascading Baroque stairway that climbs 116 metres.

Joseph I of Portugal and his Prime Minister Sebastião de Melo, Marquis of Pombal hired architects and engineers to rebuild the damaged portions of Lisbon, including the Pombaline Downtown.

It was the 1770s that ushered in the era of neoclassical architecture, with the simultaneous constructions of the Royal Riding Hall of Belém, in Lisbon, and Santo António Hospital in Porto, by John Carr.

Notable works in the northern tradition: Notable works in the southern tradition: The Neo-Manueline style, a revival style of late 16th century Portuguese Late Gothic Manueline, was the primary architectural expression of Romanticism in Portugal, owing to its highly nationalistic characteristics and history, which flourished from the middle of the 19th century to the beginning of the 20th in Portugal and Brazil, and to a lesser extent other parts of the Lusofonia (Portuguese speaking world).

The style, which rose during a time of Romantic nationalism, heavily features Portuguese national symbols, including the armillary sphere, the Cross of the Order of Christ, and elements of the Coat of arms of Portugal, as well as symbols of the Portuguese Discoveries, such as twisted ropes, exotic fruits and vegetables (like pineapples and artichokes), sea monsters, and sea plants (like coral and algae branches).

The style's popularity in Portugal was vastly concentrated in Lisbon and the Portuguese Riviera, and the southern regions of the Algarve and the Alentejo, as these had the most visible Moorish heritage in the country.

The style's expression in the North of Portugal is primarily used in interior design, such as the sumptuous Sala Arabe of Palácio da Bolsa, in Porto, or is heavily altered and mixed with other revival styles and trends in building exteriors, like Porto's Devesas Factory Warehouse Cast-iron architecture, known simply as iron architecture in Portuguese (arquitetura de ferro), largely began to manifest during the last quarter of the 19th century.

While revolutionary in regards to technical advancement, structural integrity, and other engineering feats, the stylistic trends of iron architecture were almost completely based in historicism and revival styles.

[8] The Fundação Calouste Gulbenkian, built in 1960s and designed by Rui Atouguia, Pedro Cid, and Alberto Pessoa, is one of the very best, defining examples of 20th-century Portuguese architecture.