The plan of Saint Gall, the largest known architectural drawing of the High Middle Ages that was never built

The abbey of Saint Gall ( Sankt Gallen in German) was founded in the year 613 in the town that today bears his name in Switzerland by an Irish monk, Gallus of Hibernia. It would be one of the main Benedictine monasteries in Europe for many centuries.

Aerial view of the Abbey of Saint Gall today / photo Hansueli Krapf en Wikimedia Commons

It flourished under the patronage of Pepin the Short and his son Charlemagne as a centre for the study of arts and sciences, and came to house an important library of manuscripts that monks from all over the continent came to copy. The collection is still preserved and, with nearly 160,000 volumes, is the oldest in Switzerland. The current room, built in the 18th century, is considered one of the most beautiful libraries in the world.

Plan of Saint Gall / photo public domain on Wikimedia Commons

Among the treasures it contains is the so-called Plan (or floor plan) of Saint Gall, an architectural drawing unparalleled in the whole of the High Middle Ages and a good part of the Lower Period. In fact, it is the only great architectural design that survived between the fall of the Western Roman Empire and the 13th century.

It dates from 820-830 AD, when the abbey was under the control of Emperor Louis the Pious, son of Charlemagne. And besides being unique in its kind for a period of about 700 years, it has other interesting particularities, such as: it is not known who designed it or why, the project was never built, and the monks used it in the 12th century to write the life of Saint Martin behind it. But there is more.

The plan was drawn on five scrolls sewn together and has dimensions of 113 by 78 centimeters. It represents a monastic complex drawn in red ink, with its abbey church, cloister, abbot’s house and monks’ quarters, school, guest house, house for pilgrims, novitiate, stables, kitchens, workshops, brewery, infirmary, cemetery, orchard and gardens. According to calculations made by experts, the planned complex could accommodate about 110 monks, 115 visitors and 150 craftsmen and farmers.

Detail of the cloister section / photo public domain on Wikimedia Commons

More than 300 inscriptions describing the functions of each of the buildings were added in brown ink. They were made by two different scribes and, by comparison, it has been possible to determine that they were monks belonging not to Saint Gall but to the nearby (about 52 kilometers to the northwest) Reichenau monastery, founded in 724 and located on the island of the same name in Lake Constance (in the current German state of Baden-Württemberg). Furthermore, one of the scribes has been identified as the monk Reginbert, the Reichenau librarian who wrote the codex of the Symbol Library around 820.

The dedication of the plan / photo Horn/Born, The Plan of St.Gall, t.1, p.8, fig.2

The plan is dedicated to Abbot Gozbertus or a monk of the same name who lived in the monastery at that time:

Haec tibi dulcissime fili cozb(er)te de posicione officinarum paucis examplata direxi, quibus sollertiam exerceas tuam, meamq(ue) devotione(m) utcumq(ue) cognoscas, qua tuae bonae voluntari satisfacere me segnem non inveniri confido. Ne suspiceris autem me haic ideo elaborasse, quod vos putemus n(ost)ris indigere magisteriis, sed potius ob amore(m) dei tibi soli p(er) scrutinanda pinxisse amicabili fr(ater)nitatis intuitu crede. Vale in Chr(ist)o semp(er) memor n(ost)ri ame(n).

For thee, my sweetest son Gozbertus, have I drawn this briefly annotated copy of the layout of the monastic buildings, with which you may exercise your ingenuity and recognize my devotion, whereby I trust you do not find me slow to satisfy your wishes. Do not imagine that I have undertaken this task supposing you to stand in need of our instruction, but rather believe that out of love of God and in the friendly zeal of brotherhood I have depicted this for you alone to scrutinise. Farewell in Christ, always mindful of us, Amen

There are two theories as to why the Plan was drawn. Some historians, such as Walter Horn and Ernest Born, believe that it is a copy of the original plan created at the court of Louis the Pious. The monarch would have wanted to establish a network of monasteries in his empire, thus giving guidelines on how they should be built in accordance with Benedictine rule.

Diagram of the plan published in a book by Mackenzie E. Walcott in 1861 / photo public domain on Flickr

Others, such as Werner Jacobsen, Norbert Stachura and Lawrence Nees, maintain that the plan is an original work, made in the Reichenau monastery, perhaps commissioned by the Abbot of Saint Gall, who wanted to build a new church for his abbey in the 820s. They base this on the fact that the parchment shows marks of having used compasses, and that changes and alterations made during the drawing process can be seen. In fact, it is known that work on the construction of a new church began in the year 830.

Reichenau was at that time a royal monastery, dependent on the crown, while Saint Gall belonged to the Bishop of Constance. Furthermore, according to Alfons Zettler, the lower part of the plan shows a large royal palace, something only present in large royal monasteries such as Saint-Denis. However, it does not appear under that name, but is labelled as a guest house. Zettler believes that the existence of another building, a hospice for pilgrims and beggars, on the other side of the church, suggests that the former was actually intended to house a visit by the monarch.

Reconstruction according to the plan, drawn by Johann Rudolf Rahn in 1876 / photo public domain on Wikimedia Commons

It is also not very clear what scale the plane is drawn to, whether it is a single scale for the whole or some elements are on a different scale. Generally it is accepted 1:192, which would correspond to 116 of a foot. What the experts do agree on is that there is a differentiation of spaces according to social status. Lynda Coon found that the northwest area comprises buildings reserved for the secular elites, while the southwest area would correspond to the lower classes. On the other side, the sacred zone is also divided, with the northeast and southeast areas for the monastic elite, and the more distant east and south areas for the novices.

Today it is considered that the plan does not show the layout or plan of a specific Carolingian monastery, and that the monastic complex represented was not intended to be built in Saint Gall or elsewhere. It was a vision of what a large royal abbey should look like, conceived in the particular political situation of the Regnum Alamannorum between the abbeys of Reichenau and Saint Gall in 829-830.

Model based on the plan of Saint Gall, at the Reichenau tourist office / photo Wolfgang Sauber on Wikimedia Commons

A few years ago, a group of enthusiasts in Meßkirch, Baden-Württemberg, very close to Lake Constance, created a construction project to carry out what is depicted in the plan of Saint Gall. They are using techniques and tools of the time, and since 2013 the site is open to the public as a theme park (with restaurants, accommodation and so on), in order to finance the work. On their official website there is a version of the plan in which you can see what function each building had.


Sources: The Plan of St. Gall: A Study of the Architecture & Economy of, & Life in a Paradigmatic Carolingian Monastery (Walter Horn, Ernest Born) / Spaces for servants and provendarii in Early Medieval Monasteries. The example of the virtual monastery of the Plan of Saint Gall (Alfons Zettler). Bulletin du centre d’études médievales d’Auxerre, BUCEMA (Hors-série no.8). doi:10.4000/cem.13624 / The Plan of Saint Gall and the Theory of the Program of Carolingian Art. Gesta. 25:1–8. JSTOR 766891 / Nouvelles perspectives pour le Plan de Saint Gall (M.Carol Heitz). Bulletin de la Société Nationale des Antiquaires de France pour 1992: 169–173. doi:10.3406/bsnaf.1994.9735 / Wikipedia.