The most important building types in the Middle Ages were churches and cathedrals. Religion was the most important aspect in the life for all people and the Catholic church had the resources to undertake large building projects.

After the fall of the Roman empire the Roman cities lay partly deserted and fell to ruins. New cities emerged from the Roman remains but also around the new palaces of kings. Bishops and their residences gave rise to new cities too. The walled cities contained mostly small, simple houses, but with the rise of the middle classes from the 11th Century onward larger and more elaborate houses were built in many local styles. City halls and market halls were built, often both in one building with the council house on top of a market with open arcades to a square. The builing usually was placed in the center of the main square. City halls represented the middle classes and therefore were often elaborately decorated to underline their influence., The buildings of different guilds tried to each be more beautiful than the other.

Carolingian Architecture

In the year 800 Charlemagne was crowned emperor by the pope. He was the first emperor of western Europe after the fall of the Roman empire.. He saw himself as successor of the Roman emperors and counterpart of the Byzantine emperors who ruled in the east. As such he looked back at antiquity and studied it.

During the early and high Middle Ages kings and emperors would travel between their different palaces with their household and all their belongings, including furniture. They did not have one fixed abode. The palaces were built in the spirit of Roman and Byzantie palaces and called 'Pfalzes'. A Pfalz was a large walled complex consisting of halls, living and service rooms, a chapel and sometimes a writing school(also called scriptorium) that produced books. Until the 13th Century over 100 such palaces were built all over the empire.

Since 786 the capital of Charlemagne's kingdom was Aachen¹, which at this time was also known as 'nova Roma'. The local Pfalz included the Pfalzkapelle (palace chapel), the only remaining large building of Carolingian times. The Pfalzkapelle was a church that now forms the core of today's cathedral. The original building is perfectly octogonal in its center and topped by a dome. Around this structure runs a 16-sided a gallery on 2 storeys. The galleries are connected to the central hall through arcades. The entrance building of the church was decorated with original antique columns from Rome and Ravenna, which was an expression of the wish to renew the antique traditions². The whole building is inspired by Byzantine architecture.

In the long run the basilica turned out to be the prevailing shape for churches. This building type took its shape from the antique Roman basilica. It had a high, long nave with lower aisles on both sides. This shape allowed windows to bring light through the upper part of the nave as well as the aisles and therefore make the large interior brighter. The entrance or multiple entrances were on the narrow western side of the building.³ This entrance side had the appearence of a seperate building with towers and was often built on a square floorplan in the manner of Byzantine churches. This so-called westwork was used for instance for batisms and had a gallery on the upper floor from where masses could be watched. On the opposite side of the church was the apse, a half circular extension of the nave. In front of the apse the altar was located. This position opposite of the entrance immediately focuses everyone's view to the place of the religious acts of the priest. Usually this space was also raised a few steps higher than the major part of the building.

Early Christian basilicas sometimes had a transept, which became a more and more popular feature. The transept is a corridor running in a 90° angle to the nave and aisles. This gave the church a cross shaped floor plan. Between the intersection of the nave and the transept and the apse the quire (or choir) was located, a place reserved for monks and priests. They were the only people in the church who got chairs or benches. Above this intesection a tower was added to the roof of the church. The basilica could also get a symmetrical layout with two transepts, two qures, two apses and two towers.

After Charlemagne visited Montecassino, the original Benedictine monstery founded by St. Benedict, he started to establish monasteries of this order in his empire. Benedictine monks became an important factor of economy and power in the whole western world.

The oldest architectural drawing known from after antiquity dates from the year 820 and shows the monastery of St Gallen, Swizerland. In simple lines it depicts the ideal layout of a monastery with a church. The whole site resembled a small town. A square courtyard was surrounded by a covered walkway – the cloister. The church was situated on one of its sides while the other three sides were occupied by all buildings necessary in the monks' lives. The monastery also included sheds for various animals and houses for their keepers, a brewery, a bakery and kitchens. There were separate buildings for tending to the sick and for guests as well as a school.

Dozens of cathedrals and hundreds of monasteries were built during the reign of Charlemagne.

Romanesque

In the 9th Century Charlemagne's efforts to recreate antiquity came to an end and the knowledge about antique building technology was lost. A new style emerged in the middle of the 10th Century. Romanesque was the first major architectural style used after antiquity and with some regional differences was used all over western Europe. It got its name because it looked back on Roman shapes like pillars, arches and vaults. It did not however originate in Italy but came from Germany and France. The great achievement of Romanesque was that all buildings were designed systematically by looking at all parts of the building: floor plan, walls and ceilings.

Buildings began to be organised in modules which were rhytmically arranged. From about 1100 onwards these modules were not separated into walls, ceilings and floor plans but were fully 3-dimensional. One so-called 'bay' had the dimensions of the intersection of nave and transept. It was built up of four columns as well as the parts of the ceiling they carried and the exterior church walls between them. This module was serially added along the length of the nave - meaning one bay was joined to the next in a long series. Soon the modules would also encompass the shape of the aisle, with one bay in the nave adjoyining two smaller modules in the aisles. Even alternating arangements of square and rectangular modules became possible.

The facades of churches stopped being plain surfaces but were structured with various horizontal and vertical decorative elements. Windows with round arches, friezes of arched ornaments and pillars shaped the facades. Below the roof there sometimes were fake galleries built up of small arcades⁴ which made the facade look more 3-dimensional.

Usually the quir and apse were parted from the area for ordinary persons by a high wall which was decorated with pictures. Most of these walls were removed in later centuries.

The church portals often gained two small towers above them. The arched portals themselves were set into a recess, first getting more narrow like a funnel, then stepped. They were often decorated with ornaments and sculptures.

Especially in northern France, England and southern Italy the interior of the walls started to be decorated in 3 levels. The lower level were the arcades parting the nave from the aisles, above them was a second level of solely decorative arcades and the last level formed the arched windows of the nave. The arcades of the upper levels were set in front of the walls like a 2nd layer to create depth.

Ceilings originally were built as simple barrel vaults, which distribute their whole load evenly on the exterior walls. The required thickness of the walls gave the buildings a rather 'heavy' look. Sometimes the walls even needed reinforcements on the outside. Often the vaults were higher than wide to make them more stable. Later two intersecting barrel vaults shaped crossing ridges on the ceiling which ran from one supporting pillar to the next. This distributed the weight of the ceiling mainly on the pillars. Finally the ridges were reinforced with stone ribs which continued to run down the pillars. All weight ran through these ribs and down the pillars. The vaults between the ribs had no structural function themselves. This innovative system later became typical for the Gothic period.

The modular system of building parts and systematic rhytmical arrangements of the Romanesque period became a formative aspect in western architecture.

Gothic

The new Gothic⁵ style was developed in the 12th Century in France and from there spread over western and central Europe, while not being used in all parts of southern Europe. North of the Alps it stayed the prevailing style of architecture until the 16th Century.

The Gothic style took all parts of the perfected Romanesque style and transformed it to a new architectural system. The room modules were not mostly square anymore but a longer rectangle. The rows of columns got more narrow in relation to a wider nave. Arches, vaults and windows became higher and higher and gained pointed tops. This made the pointed arch one of the most recogniseable elements of Gothic architecture. Through the use of rib vaults, columns and pillars the whole building was carried by a stone skeleton. The largest part of the surface of the walls was now not a load bearing element anymore, which made it possible to cut large openings into them. Only because of this the impressive Gothic glass windows were possible. Light became an important aspect of religious architecture.

Pillars on the inside of the building however were not enough to carry the large roofs. Systems of pillars and arches on the outside of the churches helped to carry the pressure of the vaults going sideways. These so-called buttresses could sometimes get impressive dimensions with multiple layers of arches and pillars supporting each other.

The whole church was getting higher, with an emphasized verticality instead of the rather squat shapes of the Romanesque period. Depending on the geographic location the large towers either had flat tops or high spires. A very large variety of different intricate onaments appeard all over the building together with statues and colorful windows. Next to the windows with pointed arches also large round windows appear, often above the entrance.

In the late Gothic period hall churches became popular. In this kind of buildings the aisles have the same height as the nave and so create one large hall.

Dawn of a new age

While the Gothic period was still in fashion in the 14th Century in northern Europe, it was never quite the style of the Italians. They were busy laying the foundations of the Renaissance, which took quite a while to reach the lands in the north.