In Assassin's Creed Unity, Paris's Notre-Dame cathedral is recreated as a major landmark.
The game is set during the French Revolution and lets players explore a detailed version of Paris, including the Île de la Cité and the cathedral commonly known as Notre-Dame de Paris. The building is used as an explorable location and as part of the game's historical atmosphere, rather than serving only as a distant background object.
Notre-Dame is a medieval Gothic cathedral whose construction began in the 12th century. Its prominent position on an island in the Seine made it a natural landmark for a game focused on movement through revolutionary Paris. Unity's depiction predates the 19th-century restoration changes associated with architect Eugène Viollet-le-Duc.
Sainte-Chapelle is also on the Île de la Cité, which can lead to confusion, but it is a separate Gothic chapel. Montmartre Basilica and Les Invalides are different Paris landmarks and do not provide the requested answer.