Italian architecture

Italy has a very broad and diverse architectural style, which cannot be simply classified by period or region, due to Italy's division into various small states until 1861. This has created a highly diverse and eclectic range in architectural designs. Italy is known for its considerable architectural achievements, such as the construction of aqueducts, temples and similar structures during ancient Rome, the founding of the Renaissance architectural movement in the late-14th to 16th century, and being the homeland of Palladianism, a style of construction which inspired movements such as that of Neoclassical architecture, and influenced the designs which noblemen built their country houses all over the world, notably in the United Kingdom, Australia and the United States of America during the late-17th to early 20th centuries.
Several of the finest works in Western architecture, such as the Colosseum, the Duomo of Milan, the Mole Antonelliana in Turin, Florence Cathedral and the building designs of Venice are found in Italy. Italy has an estimated total of 100,000 monuments of all varieties. Now Italy is in the forefront of modernist and sustainable design with architects like Renzo Piano and Carlo Mollino.
Italian architecture has also widely influenced the architecture of the world. Moreover, Italianate architecture, popular abroad since the 19th century, was used to describe foreign architecture which was built in an Italian style, especially modelled on Renaissance architecture.

Magna Graecia and the Etruscans

Along with pre-historic architecture, the first people in Italy to truly begin a sequence of designs were the Greeks and the Etruscans. In Northern and Central Italy, it was the Etruscans who led the way in architecture in that time. Etruscan buildings were made from brick and wood, thus few Etruscan architectural sites are now in evidence in Italy, with the exception of a few in Volterra, Tuscany and Perugia, Umbria. The Etruscans built temples, fora, public streets, aqueducts and city gates which had a significant influence on Roman architecture.
In Southern Italy, from the 8th century BC, the Greek colonists who created what was known as Magna Graecia used to build their buildings in their own style. They built bigger, better and technologically advanced houses which influenced Roman architecture too. Yet, by the 4th century BC, the Hellenistic Age, less concentration was put on constructing temples, rather more time was spent building theatres. The theatres were semi-circular and had an auditorium and a stage. They used to be built only on hills, unlike the Romans who would artificially construct the audience's seats.
The Greek temples were known for containing bulky stone or marble pillars. Today, there are several remains of Greek architecture in Italy, notably in Calabria, Apulia, and Sicily. The temples in the Valle dei Templi, which are currently UNESCO World Heritage Sites, are a fine example.

Ancient Rome

Influenced by Greek architecture and by the Etruscan architecture, Roman architecture assumed its own characteristics.
The Romans absorbed Greek influence, apparent in many aspects closely related to architecture; for example, this can be seen in the introduction and use of the triclinium in Roman villas as a place and manner of dining. The Romans, similarly, were indebted to their Etruscan neighbours who supplied them with a wealth of knowledge essential for future architectural solutions such as hydraulics and in the construction of arches.
Social elements such as wealth and high population densities in cities forced the ancient Romans to discover new solutions of their own. The use of vaults and arches, together with a sound knowledge of building materials, enabled them to achieve unprecedented successes in the construction of imposing structures for public use. Prominent examples include the aqueducts of Rome, the Baths of Diocletian, and the Colosseum. These were reproduced at smaller scale in major towns and cities throughout the Empire, with some structures surviving almost completely intact, such as the town walls of Lugo in Hispania Tarraconensis.

Early Christian

Italy was widely affected by the Early Christian age, with Rome being the new seat of the pope. After the Justinian reconquest of Italy, several buildings, palaces and churches were built in the Roman-Byzantine style. The Christian concept of basilica was invented in Rome. They were known for being long, rectangular buildings, which were built in an almost ancient Roman style, often rich in mosaics and decorations. The early Christians' art and architecture was also widely inspired by that of the pagan Romans; statues, mosaics and paintings decorated all their churches. Late-Christian frescos can be easily seen in some of the many catacombs in Rome.
Early Christian churches in Milan are the first churches built immediately after the Edict of Milan in February 313, issued by Constantine the Great and Licinius, which granted tolerance and religious liberty to Christianity within the Roman Empire. The early Christian basilicas in Mediolanum can be divided into several categories, corresponding to their periods. The first basilicas we know are divided into two separate churches, one for the baptized, being the sacrament of baptism at that time granted only upon completion of a process of conversion and spiritual purification, and the other for catechumens. This particular arrangement perhaps derived from horrea, a type of public warehouse used during the ancient Roman period, such as the ancient buildings of Aquileia. The Basilica di Santa Tecla, whose ruins can be visited under the Milan Cathedral, has apse of traditional type, reminiscent of those of the churches annexed to great civic buildings. The religious center of the city, now Piazza del Duomo, included two cathedrals: the basilica vetus or basilica minor, used during the winter season, and basilica nova or basilica major, used during the summer. With the Roman governor and bishop Ambrose began a program to build basilicas dedicated to various categories: a basilica for the prophets, one for the apostles, one for the martyrs, one for the virgins.

Byzantine architecture

was also widely diffused in Italy. When the Western Roman Empire fell in 476 AD, the Byzantines were the leaders in the world regarding aspects of culture, arts, music, literature, fashion, science, technology, business and architecture. The Byzantines, which technically were the people of the Eastern Roman Empire, kept Roman principles of architecture and art alive, yet gave it a more Eastern twist, and were famous for their slightly flatter domes, and richer usage of gilded mosaics and icons rather than statues. Since the Byzantines resided in Sicily for some time, their architectural influence can still be seen today, for example in the Cathedral of Cefalu, Palermo, or Monreale, with their richly decorated churches.
The term "Italo-Byzantine" is used for sculpture much less often, as the Byzantines did not provide large models to follow for that. It may be used of ivories, mosaics and the like. In architecture it is the almost inevitable term used for San Marco, Venice, and a few other very old buildings in Venice and on the small islands of Torcello and Murano in the lagoon, but is not often used for other buildings. Even the rest of Venetian Gothic architecture does not owe much to Byzantium. St Mark's Basilica in Venice is also an example of Byzantine architecture in Italy. It is one of the best known examples of Italo-Byzantine architecture

Romanesque architecture

Between the Byzantine and the Gothic period was the Romanesque movement, which went from approximately 800 AD to 1100 AD. This was one of the most fruitful and creative periods in Italian architecture, when several masterpieces such as the Leaning Tower of Pisa in Piazza dei Miracoli and the Basilica of Sant'Ambrogio in Milan were built. The style was called "Roman"-esque because of its usage of the Roman arches, stained glass windows, and also its curved columns which commonly featured in cloisters.
Romanesque architecture varied greatly in Italy in both style and construction. Arguably, the most artistic was the Tuscan Romanesque, especially Florentine and Pisan, yet that of Sicily, influenced by the Norman settlers, was considerable too. Lombard Romanesque was certainly more structurally progressive than the Tuscan but less artistic.
Romanesque architecture in Italy halted the construction of wooden roofs in churches, and also experimented with the usage of the groined vault or barrels. The buildings' weight tended to buckle on the outside, and there used to be buttresses to support the buildings. Church walls using the Romanesque tended to be bulky and heavy to support the roof, however this meant that Romanesque church interiors in Italy tended to be far more banal and bland than those of the Early Christian and Byzantine periods. They used to simply consist of marble or stone, and had little decoration, unlike the rich mosaics found in Italian Byzantine architectural works.
The main innovation of Italian Romanesque architecture was the vault, which had never been seen before in the history of Western architecture.

Gothic architecture

The Gothic architecture appeared in Italy in the 12th century. Italian Gothic always maintained a peculiar characteristic which differentiated its evolution from that in France, where it had originated. In particular, the bold architectural solutions and technical innovations of the French Gothic never appeared: Italian architects preferred to keep the construction tradition established in the previous centuries. Aesthetically, in Italy the vertical development was rarely important.
Gothic architecture was imported in Italy, just as it was in many other European countries. The Benedictine Cistercian order was, through their new edifices, the main carrier of this new architectural style. It spread from Burgundy, their original area, over the rest of Western Europe.
A possible timeline of Gothic architecture in Italy can comprise:

an initial development of the Cistercian architecture
an "early Gothic" phase
the "mature Gothic" of 1290–1385
a late Gothic phase from 1385 to the 16th century, with the completion of the great Gothic edifices begun previously, as the Milan Cathedral and San Petronio Basilica in Bologna.