Basilique de l'Immaculée Conception, Minor basilica in Ouidah, Benin.

The Basilique de l'Immaculée Conception is a church with Gothic Revival architecture featuring a straightforward nave, a transept running across the width, and distinctive vertical design elements. The interior spaces create an orderly, soaring effect through arched proportions and the careful arrangement of architectural details typical of this revivalist style.

Bishop Louis Dartois, first apostolic vicar of Dahomey, had the plans drawn up and laid the first stone on 30 August 1903; work stopped at his death in 1905. His successor François Steinmetz, called "Daga" for his height, resumed building with help from Vodoun followers as well as Christians, and the cathedral was consecrated on 9 May 1909 before some 4,000 people. It became a minor basilica on 9 November 1989.

The church was first planned as a cathedral dedicated to the Sacred Heart, but was finally dedicated to the Immaculate Conception, a Marian devotion brought to Ouidah by the Portuguese in 1648; a marble plaque inside recalls this. The building stands on the site of the former Agore, seat of the representative of the kings of Dahomey and a place where Christians were once held.

The basilica stands in the Agori quarter, on the site of the former Agore, seat of the representative of the kings of Dahomey. The main altar rests above a well nearly seven metres deep where human remains were found during excavation of the foundations. The building has a single nave of five bays lit by twin windows topped with oculi.

The site was once the Agore, seat of the representative of the Kings of Dahomey and a place where Christians were held. During excavation of the foundations, human remains were found at the bottom of a well nearly seven metres deep; the main altar now stands on that exact spot.