According to some early sources, such as the Abbot Leboeuf, the original baptistry was located next to the Seine, but more recent research suggests that it was always at the same site of Saint-Le-Rond.

[1] In the 12th century, the church is recorded as having two priests, who were in charge preaching to servants of the chanoines, or canons, and the sergeants who maintained the cathedral, as well as to the non-clerical staff who lived in the cloisters.

[2] Later, in the 13th century, after the demolition of the Cathedral of Saint Etienne and the construction of Notre-Dame de Paris, the church was rebuilt in rectangular form.

[3] The new church was rectangular rather than square, and had a triangular gable on the west front, a console with archivolts, and columns whose capitals were decorated with sculptures of leaves gathered into large balls.

Another motivation was a program to reduce the number of small parishes in the Ile-de-la-Cité, Therefore, the functions of the curé, the baptistry and the canons were transferred to another church east of the cathedral, Saint-Denis-du-Pas.