The most famous architectural element of the church is its north portal (the "Schottenportal"), which occupies a full third of the north wall, and is richly decorated with both ornamental and figural sculptures. The proper interpretation of this sculptural program has been debated since the beginning of the 19th century. In the 1990s it was suggested that only the tympanum, archivolt, and jambs formed an original composition of the 12th century, while the remaining portions of the "Schottenportal" were assembled from spolia during the Renaissance. While this theory would have absolved art historians of the duty of interpreting the program as a unified whole, it has not met with wide acceptance. Indeed, a thorough examination of the structure seems to have demonstrated conclusively that the entire portal was assembled in the late 12th century, simultaneously with the construction of the second church.