Situated near the site of Paris' medieval marketplace (Les Halles) and rue Montorgueil, Saint-Eustache exemplifies a mixture of multiple architectural styles: its structure is Flamboyant Gothic[1] while its interior decoration[2] and other details are Renaissance and classical.

Situated in Les Halles, an area of Paris once home to the country's largest food market, the origins of Saint Eustache date back to the 13th century.

[3] The small chapel was funded by Jean Alais, a merchant at Les Halles who was granted the rights to collect a tax on the sale of fish baskets as repayment of a loan he gave to King Philippe-Auguste.

He was a passionate hunter; his conversion followed a vision he had of a crucifix in the horns of a deer he was hunting, He was martyred, along with his family, for converting to Christianity.

Construction of the current church began in 1532, during the reign of François I and continued until 1632, and in 1637, it was consecrated by Jean-François de Gondi, Archbishop of Paris.

Although the architects are unknown, similarities to designs used in the extension of the church of Saint-Maclou in Pontoise (begun in 1525) point to Jean Delamarre and/or Pierre Lemercier, who collaborated in that work.

The addition of two chapels in 1655 severely compromised the structural integrity of the church, necessitating the demolition of the facade, which was rebuilt in 1754 under the direction of the architect Jean Mansart de Jouy.

[5][4] Baltard directed a complete restoration of the building from 1846 to 1854, including the construction of the organ case, pulpit, and high altar and the repair of the church's paintings.

[6] The church was set afire during the Semaine sanglante, the last battle of Paris Commune in May 1871, necessitating repairs to the attic, buttresses, and south facade.

The Gothic exterior elements are the elaborate flying buttresses, which receive the downward and outward thrust from the rib vaults in the interior.

The most Gothic portion is the apse at the east end, where the buttresses surround semicircular group of chapels, located behind the altar.

The south portals primarily decorated in the Renaissance style, with a profusion of ornamental sculpture in the form of foliage and seashells.

The Flamboyant Gothic elements are primarily in the vaulted ceilings decorated with a network of ornamental ribs and hanging keystones.

Below are the Renaissance elements, in the form of pillars and pilasters representing the classical orders of architecture, rounded arcades, and walls covered with elaborate decorative sculpture of seraphim and bouquets of flowers.

[15] The nave is flanked by two collateral aisles, which give access to series of small chapels, each abundantly decorated with paintings and sculpture.

One of the notable classical features of the nave is the Banc-oeuvre, a group of seats covered a Grecian portico and very ornate carvings.

[15] The central work in this chapel, "The Ecstasy of Saint Madeleine", was made by Rutilio Manetti in the early 17th century, in a style where the drapery emphasizes the contrasts between darkness and light.

[16] The major work in this chapel is "Tobias and the Angel", a mannerist painting from the late 16th century by the Tuscan Santi di Tito (1536-1603).

It depicts, in a humorous way, a procession of merchants carrying fruits and vegetables from the Les Halles markets that formerly were located across the street from the church.