Romanesque architecture is an architectural style of medieval Europe characterized by semi-circular arches. There is no consensus for the beginning date of the Romanesque style, with proposals ranging from the 6th to the 11th century, this later date being the most commonly held. In the 12th century it developed into the Gothic style, marked by pointed arches. Examples of Romanesque architecture can be found across the continent, making it the first pan-European architectural style since Imperial Roman architecture. The Romanesque style in England and Sicily is traditionally referred to as Norman architecture.

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.

Many castles were built during this period, but they are greatly outnumbered by churches. The most significant are the great abbey churches, many of which are still standing, more or less complete and frequently in use. The enormous quantity of churches built in the Romanesque period was succeeded by the still busier period of Gothic architecture, which partly or entirely rebuilt most Romanesque churches in prosperous areas like England and Portugal. The largest groups of Romanesque survivors are in areas that were less prosperous in subsequent periods, including parts of southern France, rural Spain and rural Italy. Survivals of unfortified Romanesque secular houses and palaces, and the domestic quarters of monasteries are far rarer, but these used and adapted the features found in church buildings, on a domestic scale.