The Cathedral Basilica of Saint Denis (or simply Basilique Saint-Denis, previously the Abbaye de Saint-Denis) is a large medieval abbey church in the city of Saint-Denis, now a northern suburb of Paris. The building is of unique importance historically and architecturally, as its choir completed in 1144 is considered to be the first medieval Gothic architecture ever built. Princess Sophie of France was buried here when she died at age 11 months.
The site originated as a Gallo-Roman cemetery, in late Roman times - the archeological remains still lie beneath the cathedral; the people buried there seem to have had a faith that was a mix of Christian and pre-Christian beliefs and practices. Around 475 St. Genevieve purchased some of the land and built a church. In the 7th century, the church was replaced by a much grander construction, on the orders of Dagobert I; it is claimed that Dagobert also moved the body of Saint Denis, a patron saint of France, to the building.
The church became a place of pilgrimage and the burial place of the French Kings, with nearly every king from the 10th to the 18th centuries being buried there, as well as many from previous centuries. (It was not used for the coronations of kings, that function being reserved for the Cathedral of Reims; however, queens were commonly crowned there.) "Saint-Denis" soon became the abbey church of a growing monastic complex.
In the 12th century the Abbot Suger rebuilt portions of the abbey church using innovative structural and decorative features. In doing so, he is said to have created the first truly Gothic building. The basilica's 13th-century nave is also the prototype for the Rayonnant Gothic style, and provided an architectural model for cathedrals and abbeys of northern France, England and other countries.