Minster of St. Mary and Mark with Treasury, Reichenau Island

St. Mary and St. Mark's Minster with treasury and monastery gardens
The oldest church on the island is St. Mary and St. Mark's Minster, the former monastery church (founded in 724). The simple wooden building of the monastery's founder Pirmin became too small after just a few decades and was replaced by a 40 m long stone building in the 8th century. To the north of this, i.e. opposite the convent buildings that are still visible today, there was a cloister and a two-storey monks' house. These buildings were soon expanded too, because in the middle of the 9th century the island convent had 134 monks.
While this monastery complex has only been preserved in underground traces, we can still trace the stages of development of the abbey church today. The eastern transept and the crossing arches come from the three-aisled cross basilica consecrated in 816, which Abbot Heito I had built. While Heito's crossing building remained unchanged for a long time, the western part of the abbey church was rebuilt several times. The westwork received its current appearance under Abbot Berno. It was consecrated shortly before his death in 1048 in the presence of Emperor Henry III.
After the decline of the abbey, regular monastic life only began again with Abbot Friedrich von Wartenberg (1427-1435). He began building the Gothic choir in the east of the cathedral, which was not completed until the painting in 1555. After incorporation into the diocese of Constance in 1540, the monastery continued to exist as a priory. Prince-Bishop Jakob Fugger had new convent buildings built on the south side of the cathedral from 1605 to 1610. After the complex was completed, the "Old Monastery" on the north side was demolished. The monastery was dissolved in 1757. The Fugger "new" convent buildings now serve as a rectory and the seat of the municipal administration. The winegrowers' association presses Reichenau wine in the spacious cellar.
In the cathedral's treasury, numerous reliquaries and other cult objects from the 5th to 18th centuries can be seen.
Text / Source: Roman Catholic parish of Reichenau
kath-reichenau.de/die-katholischen-kirchen-der-insel-reichenau-2/muenster-st-maria-und-markus-4

Monastery history
Saint Pirmin founded the Reichenau monastery in 724. It became one of the most important religious, cultural and political centers of the Middle Ages. The knowledge of humanity was collected in the libraries. The detailed monastery plan that was created on Reichenau, is kept in St. Gallen and is now being implemented on the medieval construction site of Campus Galli near Meßkirch. Or the "Hortulus" by Abbot Walahfrid Strabo, the first guide on the subject of gardening, in which 24 medicinal and culinary herbs are described. The corresponding garden is still maintained today not far from the cathedral and is open to visitors.
Text / Source: Tourist Information Reichenau, Pirminstraße 145, Reichenau Island
reichenau-tourismus.de/de/erleben/unesco-welterbe/geschichte

Decline and dissolution
By a decree under Abbot Friedrich von Wartenberg (1427-1453), the monastery, which had been reserved for the high nobility, was also made accessible to the lower nobility.
The Reichenau Abbey came to an end with Markus von Knöringen, abbot of the monastery from 1508-1516 and from 1523-1540. It was sold for a fee to the Bishop of Constance, Johann III von Weeze, who was enfeoffed with the imperial fief of the abbey by Charles V. The monastery continued to exist as a priory until it was dissolved in 1757.
Text / Source: Tourist Information Reichenau, Pirminstraße 145, Reichenau Island
reichenau-tourismus.de/de/erleben/unesco-welterbe/geschichte