It bore this inscription: “This first stone was laid by Mr. Charles de Hillerin, doctor of theology, parish priest and bishop of Saint-Médéric, in Paris, on the third day of July 1645.

Lassus determined the structure, set the iconographic program, and designed the church furniture of Belleville.

The hinges of the gate and all the side doors were forged by the artistic ironworker Pierre François Marie Boulanger.

The French architect Eugène Viollet-le-Duc said of the church: “Lassus displayed a lot of erudition, taste, and even put a certain original character into this large-scale study of the architecture of the 13th century.” [3] In 2008, the choir was the subject of work intended to create a baptistery and renovate the sanctuary, under the direction of the architect François Lacoste.

Jean-Baptiste Lassus was the first to apply the methods of archaeological examination and reasoning to Middle Ages buildings and to combine this graphic approach with the study of ancient texts.

Lassus seeks to construct a building rich in religious poetry by playing on light, the multiplicity of points of view, the variety in the unity, and the lightness of the construction: “Gothic monuments take the mind to the sky where their pyramids soar: one would believe that the artist wanted to erect so many Jacob's ladders, to put man in contact with God.

The unity strikes you first and yet each part, each detail presents you with a new combination, an arrangement as ingenious as it is unexpected, and in which each step gives you the pleasure of a discovery.

Inspiration has triumphed over all material obstacles, opened the doors to a new world.” [4] Henri Guérin (1929-2009) adopted the stained glass slab technique practiced by the Benedictine monk Dom Ephrem Socard at En-Calcat Abbey.

Henri Guérin personalized this technique by applying his painter's style to it— by removing shadows from the slabs during cutting using large, deep slivers.

He gradually refined the cement joints until he transformed them into fine mesh which he tinted in the tone, allowing its integration into the architecture.

John is presented in the New Testament as the cousin of Jesus and the prophet who prepares the coming of the Lord (Luke), as the voice announced by the prophets inviting conversion (Matthew): John preaches in the desert, announces the “good news” of the coming of the Messiah.

Central portal (work by Aimé-Napoléon Perrey): the angel Gabriel announces to Zacharias the birth of a son, Jean.

Tympanum of the left portal (alongside rue Lassus): François Nicolas Madeleine Morlot, Archbishop of Paris presents the Church of Belleville to Saint John the Baptist.

The tomb of Jesus is guarded by five soldiers: two are in admiration and prayer, another is thinking, another is running away in terror, the last is trying to pierce Christ with his spear.

The iconography, the varied typology of the glass roofs, and the techniques implemented all demonstrate the archaeological concern specific to Neo-Gothic architects.

During the consecration of the altar in 2008, relics of Saint Jean-Marie Vianney, parish priest of Ars (1786-1859), were placed there.

In 2014, the city of Paris brought the entire electrical system up to standard and lit all the small chapels.

One can now admire the bright atmosphere and elevation provided by this renovation in harmony with the wishes of the architect Lassus.