Seine-Saint-Denis is a department of France located in the Grand Paris metropolis in the Île-de-France region. In French, it is often referred t…Seine-Saint-Denis is a department of France located in the Grand Paris metropolis in the Île-de-France region. In French, it is often referred to colloquially as quatre-vingt treize or neuf trois, after its official administrative number, 93. Its prefecture is Bobigny.