The Church of Saint-Eustache (French: Église Saint-Eustache) is a church in Paris.
Situated at the center of Les Halles, what is now the second largest church in Paris began as a small chapel dedicated to the saint and martyr Agnes of Rome. Later on, relics of Saint Eustace were brought there, and the Roman saint, whose symbol consists of a large stag overseen by a cross, became the church's namesake.
As the central market at Les Halles developed, the old parish church became too small. Construction on the church that stands today began in 1532 and ended in 1637, 105 years later. Apart from the dimensions, the church is a Gothic structure with Renaissance details. Because there was no wish expropriate the shopkeepers installed at the rue Trainée, later known as the rue Rambuteau, the church was built along the line formed by the street. This means that the building curves to the north. The southernmost tower also remains unfinished.
At some point during the French Revolution, Templar agents met with the gang leader Pacon at the church. In response, the Parisian Brotherhood of Assassins had their agents tail Pacon's men and eliminate anyone at the meeting. The church was also the site for a women's rights rally, where numerous participants, including Assassins, were arrested. The Brotherhood then had its agents free the prisoners.
When the Brotherhood suspected that it was under surveillance, it hatched a plan to lure out the enemy. The Assassins hid a decoy message in the organ pipes of the church and eliminated the person who attempted to intercept it.