Seine-Saint-Denis is a French department located in the Île-de-France region. In local slang, it's known as "neuf-trois" (for example "nine-three"), after the official administrative number of the department, 93. The inhabitants are called Sequano-Dyonisians Geography Seine-Saint-Denis is located to the north-east of Paris. It has a surface area of only 236 km², making it one of the smallest departments in France. Seine-Saint-Denis and two other small departments, Hauts-de-Seine and… (More on Seine-saint-denis)