Gate Hall

Right next to the old monastery church you can see one of the oldest buildings in Bavaria, the Carolingian Gate Hall. Inside the gate hall, a cycle of frescoes by archangels can be seen, which can be regarded as a major work of the Carolingian Renaissance. The chapel room shows copies of famous art treasures from the Agilolfinger and Carolingian periods. The exhibition in the vicarage is dedicated to the Chiemsee painting.

Worth seeing is the so-called Carolingian gatehouse from the early days of the monastery, which dates back to the year 850.[5] This is a rectangular building made of tuff stone with a square extension on the east side. Its ground floor once housed a small chapel dedicated to St. Nicholas, and its upper floor was the apse of St. Michael's Chapel. During restoration work, almost life-size depictions of angels were uncovered here. Of these impressive in their simplicity, originally probably six red outline drawings, two are still almost completely preserved. They were previously dated to the 9th century, but today later. A large, barrel-vaulted passage runs through the gatehouse in the middle of the ground floor, bordered on both sides by an open row of arcades with three arches each. To the west is the baroque vicar's house.
Source and further information
de.m.wikipedia.org/wiki/Fraueninsel

Many conversions and changes of use as a school and from 1920 as an artist exhibition space make it difficult to date exactly. It is assumed that the Carolingian gate hall with the art-historically valuable St. Michael's Chapel was built under Tassilo III. was built as the entrance building in front of the monastery around the year 782, other archaeologists place the building on the 8th or 10th century.