The impressive, ornately decorated Baroque hall of the Abbey Library is considered to be the finest example of Baroque secular architecture in Switzerland and one of the most perfectly structured library buildings in the world. The Baroque hall was constructed and lavishly fitted out between 1758 and 1767 under the auspices of Prince-Abbot Cölestin Gugger von Staudach, who also commissioned the building of the Abbey church (which became the cathedral in 1823)
The ceiling frescoes depict the first four ecumenical councils of the early church: Nicaea (325), Constantinople (381), Ephesus (431) and Chalcedon (451). The lunettes over the four large window embrasures portray the Church Fathers, while the smaller cartouches represent the imparting and application of knowledge at the abbey.
The portraits of Abbots Cölestin Gugger von Staudach (who ruled from 1740 to 1767) and Beda Angehrn (who ruled from 1767 to 1796) hang on the wall at each end of the library hall. The Greek inscription ΨΥXHΣ IATPEION over the main doorway leading into the library can be roughly translated as “Sanatorium for the soul”.
The master builder Peter Thumb, originally from Bezau in Vorarlberg, and his son were responsible for the construction of the Abbey Library. The stuccoes are the work of the brothers Johann Georg und Matthias Gigl from Wessobrunn. Josef Wannenmacher from Tomerdingen (Württemberg) painted the ceiling frescoes and the monk Gabriel Loser from Wasserburg near Lindau created the wood architecture, together with his team.