Tréguier (Breton: Landreger) is a port town in the Côtes-d'Armor department in Brittany in northwestern France. It is the capital of the province of Trégor.
Tréguier is located 36 m. N.W. of Saint-Brieuc by road. The port is situated about 5½ m. from the English Channel at the confluence of two streams that form the Tréguier River.
Tréguier (Trecorum), which dates from the sixth century, grew up round a monastery founded by Saint Tudwal (died c. 564). In the 9th century it became the seat of a bishopric, suppressed on July 12, 1790 (decree of November 14, 1789). Pop. (1906), 2605.
Inhabitants of Tréguier are called trécorrois in French.
In 2008, 11.78% of primary school children attended bilingual schools.
Count Stephen of Tréguier was the second Earl of Richmond, inheriting the British peerage created by William the Conqueror for his second cousin Alan Rufus.
The United States Navy established a naval air station on 1 November 1918 to operate seaplanes during World War I. The base closed shortly after the First Armistice at Compiègne.