Colorful mosaic portrayals of Jesus and the icons of the Four Gospels shine out from the facade of the Sacred Heart Cathedral of Oran (Cathédrale du Sacré-Cœur d’Oran). Visitors who enter beneath the grand arch will find the organ, the chancel, and an altar adorned with crucifixes.

But beyond those remaining vestiges, you won’t find anything else relating to Roman Catholic worship. Deconsecrated after Algeria declared independence from France, the secularized site has served as Oran’s public library since 1996. In spite of this, traces of the church’s original function remain and provide a remarkable contrast to the city’s other former religious sites (such as the Great Synagogue, which was converted into the Abdallah Ibn Salam Mosque).

It’s well-worth joining the citizens of Oran who flock to the boulevard and the library to marvel at the mosaic facade and contemplate a structure that represents aspects of Algeria’s 20th-century history in microcosm—just keep your eyes out for pigeons overhead if you venture inside. Instead of religious services and a congregation, you’ll see shelves of books and documents in the chapel niches, and tables of students studying and socializing in what used to be the nave. Wander over to the chancel and apse areas of the ex-church, and you’re liable to encounter pigeons (and their poo).

Of further note is the fact that the cathedral, constructed between 1904 and 1913, was the first church built out of reinforced concrete in the French overseas territories. The altar is, likewise, reinforced concrete and was therefore not blessed during the cathedral’s 1930 consecration as the material is not recognized by canon law. The cathedral also serves as the setting for several poignant scenes in Albert Camus’ novel The Plague.