The church of St. Lambert was the site where Count Marquard of Eppenstein planned the erection of an abbey to the detriment of the local parish. It was only his son, Henry III, Duke of Carinthia, who was able to realize the idea in 1102-1103. The monks, it seems, came from Sankt Blasien (Black Forest). In 1109, Paschal II placed the abbey under the special protection of the Holy See, as a result of which the abbots derived quasi-episcopal rights over the vast territories that soon formed the endowment of the abbey. Among these, noteworthy are the extensive forests of Alfenz (Upper Styria); from these came the foundation of the sanctuary of Mariazell (q.v.) and of Piber and Köflach (Central Styria); territories to which the abbey dedicated centuries of pastoral and cultural care. The period of greatest flourishing of St. Lambrecht was the 14th-16th centuries.
St. Lambrecht forms a monumental and scenic complex of extraordinary picturesqueness. The church is Gothic, the convent pre-Baroque. The original Romanesque basilica was rebuilt in the form of a Hallenkirche (the largest church in Styria) from 1311-86; the furnishings, however, are Baroque (stalls, choir stalls, altars). In the vicinity arose (12th century) the rotunda of the Karner (ossuary) with its large crypt, and after 1424, the "pleban" church of St. Peter, with harmonious Gothic exterior and interior, and its intact furnishings. The monastery was then rebuilt in sumptuous style from 1693 onwards.
A unique feature of St. Lambrecht is its ornithological museum, founded by Fr. Blasius Hanf.