It is necessary to refer to the plans of other primitive churches to imagine what could have been the first church built on its site at the time of Saint-Loup, at the beginning of the 7th century; it was dedicated to Saint-Martin. Christian constructions from the 4th century were derived from the Latin basilica, with a nave without transept and an apse.
Six centuries later, the fire of 1375 destroyed the chapter archives; it was perhaps among the oldest (12th century?).
After the two fires of the 14th century, the church will not be rebuilt until the 16th century; it will be consecrated on June 5, 1712.
The vast building has harmonious proportions: 65 m long, 20 m wide at the height of the nave and 30 m at the height of the chapels, 16 m high under the vault from the nave, a little more to the chancel. Several styles coexist, Gothic (crossed warheads), Renaissance and classical.
The entrance presents a facade in the style of the architecture of the Age of Enlightenment, with a triangular pediment marked with the arms of Saint-Loup and a revolutionary inscription: "The French people recognize the Supreme Being and the 'immortality of the soul' dating from the decree of Robespierre in May 1794.
This entrance shelters a first porch covered with a cupola. A second porch surmounted by a hexagonal campanile is located under a high bell tower with a square plan; porch and tower are dated 1716. The bell tower contains 4 bells and 2 small ones for the clock. An elegant small campanile, containing a small bell surmounts the large roof of the choir.
The 3 southern chapels with roofs covered with flat tiles, are perpendicular to the axis of the choir; with the elegant staircase tower, they give the whole a beautiful look.
The choir has undergone alterations: the first pier has remained as it was erected in the 16th century. The magnificent Atlanteans date from the end of the 16th or beginning of the 17th century; the Ionic capitals could have been redone in the 18th century; a column bears the date 1802.
Note 6 large remarkable windows in grisaille and silver yellow. The axial chapel dedicated to the Virgin dates from 1547; it is polygonal in plan; its vault is of warheads, its stained glass windows from the 16th century. The furniture is interesting, enclosed benches, benches, stalls.
The 1774 organ is attributed to Joseph Rabiny. After being transformed in 1933, the instrument was restored in 2007 by the Trojan organ builder, Laurent Plet.
A plaque commemorating the refractory priests who died on "the pontoons of Rochefort": the brothers Jean-Baptiste and Sébastien Hunot and their cousin François Hunot. A young canon Jean-Baptiste Bouvret had been executed in September 1794. Abbé Fourrey left a research work concerning them, to be consulted in the archives of the library.
Saint-Loup collegiate church was listed as a Historic Monument in 1907.
From 2006, the collegiate church benefited from major restoration work.
