Prompted by plans to erect a monument commemorating around 65,000 Austrian Jews who perished in the Holocaust on the Judenplatz in Vienna, archaeological excavations were carried out in Vienna's old town during 1995-1998. Thus remains of the medieval synagogues of the Jewish community were discovered.
The first synagogue was erected in the middle of the 13th century and consisted of a freestanding one-room building. Its use as a synagogue is established by a foundation against the east wall, which supported the stairs to the Aron Hexodes or the Ark. To this “men’s Schul” (synagogue), the central room for prayer and study, an additional room was added along the north wall of the house and another one to the exterior of the southern wall. This three-room synagogue covered an area of 210 square meters. A coin minted during 1236-39 or 1246-51 that was found in the oldest floor belonging to the “men's Schul” was particularly important in dating this first building – together with the comparison of its architecture and the pottery finds with those of other sites. Very little is left of this early synagogue.
It appears that the synagogue was expanded shortly before 1294. The “men's Schul” was enlarged and turned into a double-aisled hall with three bays. In the centre of this space, between two columns, a hexagonal base of a “Bimah”, was located. Most of the fragments of glass lamps were found on the remains of the Bimah.
A third, rather thorough, rebuilding of the synagogue took place from around the middle of the 14th century onwards. It was extended as far as possible to the east and also the north room was extended to the east and fitted with colorful tile flooring. It is assumed that this north room may have housed the Yeshiva of Vienna. The most significant extension of the synagogue was to the west where most of the free space of the site was now built over.
After this extensive rebuilding, the synagogue only underwent some minor changes to its interior furnishings before its destruction in the year 1421. The synagogue covered a total area of about 465 square meters and was one of the largest known medieval synagogues.
Already at the end of the year 1420, a written document of Vienna University states that it was planned to use the stones of the synagogue for a new university building. The demolition work appears to have been well organized and aimed at reusing as much building material as possible, leaving largely only foundations and floor levels.
The reconstruction of the synagogue was made by comparing it to other medieval synagogue buildings. This was possible because a tradition in synagogue architecture emerged during the Middle Ages which dictated specific forms. Since synagogues were built by the same Christian artisans who built many other edifices in a particular region, analogies to churches and monasteries were also drawn.