Barrel vault in the context of "Diocletian's Palace"

Romanesque art is the art of Europe from approximately 1000 AD to the rise of the Gothic style in the 12th century, or later depending on region. The preceding period is known as the Pre-Romanesque period. The term was invented by 19th-century art historians, especially for Romanesque architecture, which retained many basic features of Roman architectural style – most notably round-headed arches, but also barrel vaults, apses, and acanthus-leaf decoration – but had also developed many very different characteristics.

In southern France, Spain, and Italy there was an architectural continuity with the Late Antique, but the Romanesque style was the first style to spread across the whole of Catholic Europe, from Sicily to Scandinavia. Romanesque art was also greatly influenced by Byzantine art, especially in painting, and by the anti-classical energy of the decoration of the Insular art of the British Isles. From these elements was forged a highly innovative and coherent style.

An arch is a curved vertical structure spanning an open space underneath it. Arches may support the load above them, or they may perform a purely decorative role. As a decorative element, the arch dates back to the 4th millennium BC, but structural load-bearing arches became popular only after their adoption by the Ancient Romans in the 4th century BC.

Arch-like structures can be horizontal, like an arch dam that withstands a horizontal hydrostatic pressure load. Arches are usually used as supports for many types of vaults, with the barrel vault in particular being a continuous arch. Extensive use of arches and vaults characterizes an arcuated construction, as opposed to the trabeated system, where, like in the architectures of ancient Greece, China, and Japan (as well as the modern steel-framed technique), posts and beams dominate.

Romanesque architecture is an architectural style of medieval Europe that was predominant in the 11th and 12th centuries. The style eventually developed into the Gothic style with the shape of the arches providing a simple distinction: the Romanesque is characterized by semicircular arches, while the Gothic is marked by the pointed arches. The Romanesque emerged nearly simultaneously in multiple countries of Western Europe; its examples can be found across the continent, making it the first pan-European architectural style since Imperial Roman architecture. Similarly to Gothic, the name of the style was transferred onto the contemporary Romanesque art.

Combining features of ancient Roman and Byzantine buildings and other local traditions, Romanesque architecture is known by its massive quality, thick walls, round arches, sturdy pillars, barrel vaults, large towers and decorative arcading. Each building has clearly defined forms, frequently of very regular, symmetrical plan. The overall appearance is one of simplicity when compared with the Gothic buildings that were to follow. The style can be identified right across Europe, despite regional characteristics and different materials.

A taberna (pl.: tabernae) was a type of shop or stall in Ancient Rome. Originally meaning a single-room shop for the sale of goods and services, tabernae were often incorporated into domestic dwellings on the ground level flanking the fauces, the main entrance to a home, but with one side open to the street. As the Roman Empire became more prosperous, tabernae were established within great indoor markets and were often covered by a barrel vault. Each taberna within a market had a window above it to let light into a wooden attic for storage and had a wide doorway. A famous example of such an indoor market is the Markets of Trajan in Rome, built in the early 2nd century by Apollodorus of Damascus.

According to the Cambridge Ancient History, a taberna was a "retail unit" within the Roman Empire and was where many economic activities and many service industries were provided, including the sale of cooked food, wine, and bread.

A rib vault or ribbed vault is an architectural feature for covering a wide space, such as a church nave, composed of a framework of crossed or diagonal arched ribs. Variations were used in Roman architecture, Byzantine architecture, Islamic architecture, Romanesque architecture, and especially Gothic architecture. Thin stone panels fill the space between the ribs. This greatly reduced the weight and thus the outward thrust of the vault. The ribs transmit the load downward and outward to specific points, usually rows of columns or piers. This feature allowed architects of Gothic cathedrals to make higher and thinner walls and much larger windows.

It is a type of arcuated, or arched, vault in which the severies, or panels in the bays of the vault's underside are separated from one another by ribs which conceal the groins, or the intersections of the panels. Rib vaults are, like groin vaults, formed from two or three intersecting barrel vaults; the ribs conceal the junction of the vaults.

A tetrapylon (plural tetrapyla; Greek: τετράπυλον, lit. 'four gates'; Latin: quadrifrons, lit. 'four fronts', also used in English) is a rectangular form of monument with arched passages in two directions, at right angles, generally built on a crossroads. They appear in ancient Roman architecture, usually as a form of the Roman triumphal arch at significant crossroads or geographical "focal points".

A tetrapylon was effectively a 'doubling' of the original triumphal arch form; with a total of four major arched openings, one on each side of the structure (one pair of openings opposite each other along one axis, and a second pair of openings of equal or lesser prominence perpendicular to the first pair; hence a structure with two barrel vaulted passageways, in the form of a cross). Roman examples are usually roughly square in plan, with the crossing archways of the same size; in some later examples, the plan is oblong, with the longer sides having a larger archway as for example at the Arc de Triomphe in Paris.