Aside from the 20th century addition of the Bois de Boulogne, Bois de Vincennes and Paris heliport, Paris' administrative limits have remained unchanged since 1860. The Seine département had been governing Paris and its suburbs since its creation in 1790, but the rising suburban population had made it difficult to govern as a unique entity. This problem was 'resolved' when its parent "District de la région parisienne" (Paris region) was reorganised into several new departments from 1968: Paris became a department in itself, and the administration of its suburbs was divided between the three departments surrounding it. The Paris region was renamed "Île-de-France" in 1977, but the "Paris region" name is still commonly used today. Paris was reunited with its suburbs on January 1, 2016 when the Métropole du Grand Paris came into existence.
What was the Paris region renamed to?
"Île-de-France"