Roussillon is one of the historical counties of the former Principality of Catalonia, an autonomous community of Spain with Barcelona as its capital.

The Treaty of the Pyrenees (1659) secured Roussillon and part of the Cerdanya to the French crown. During the French Revolution (1789–1799), the province of Roussillon was abolished and a new department, the Department of Pyrénées-Orientales (66), was created instead corresponding roughly to the old Roussillon. The old name of Roussillon contributed to the region of Languedoc-Roussillon, which Pyrénées-Orientales is part of today.

The region of Pyrénées-Orientales (Roussillon) nowadays, also often reffered to as Northern or French Catalonia or just "66", is French for sure but the Catalan influence is seen everywhere, i.e. the red and yellow colours of the Catalan flag, road signs in both French and Catalan language, tapas served in many restaurants etc.