Münster St. Maria und Markus

The monastery of Reichenau was founded in 724 by the itinerant monk Pirmin, with the support of Charles Martel and Duke Lantfrid. Pirmin brought forty monks to the island and had a first wooden monastic church built. Under Abbot Haito, a Carolingian basilica with a cruciform plan was constructed from 816 onwards, dedicated to the Mother of God, Mary. Around 830, relics of St. Mark the Evangelist arrived in Reichenau from Venice. Haito's successor Erlebald extended the abbey church with a nave bay, a western transept, and a twin-towered westwork. In 925, a Byzantine abbot's cross containing a Holy Blood relic enriched the monastic treasury, in whose honor a rotunda modeled after the Church of the Holy Sepulchre in Jerusalem was built by 946. The veneration of St. Mark gained importance around the turn of the millennium, leading to a comprehensive expansion of the Carolingian church under Abbot Berno. This expansion included a further western extension with a new transept and a monumental, transversely rectangular western tower, which served as a liturgical space for the Mark relics. Berno's Minster was consecrated on April 24, 1048, in the presence of Emperor Henry III. In the 13th century, the church received a barrel-vaulted oak roof structure. In the late Gothic period, the Gothic choir was built, for which the Holy Blood Chapel was demolished.

The Minster is located in the Mittelzell district on Reichenau Island in Lake Constance, in the federal state of Baden-Württemberg, Germany. The island is situated in the Untersee, a part of Lake Constance.

The Minster of St. Mary and Mark currently functions as a Catholic parish church. It is an active place of worship, celebrating two annual patronal feasts in honor of Mary and St. Mark the Evangelist, which are observed as island holidays. The church houses the tomb of Emperor Charles III ("Charles the Fat") as well as those of several abbots and Duke Gerold.

• Königsegg Castle (Schloss, approx. 778 m away)
• Windeck Castle (Schloss, approx. 1786 m away)
• Arenenberg Castle (Schloss, approx. 2934 m away)
• Hegne Castle (Schloss, approx. 3148 m away)