Saint-Cast-le-Guildo is a historic commune in the Côtes-d'Armor department of Brittany, northwestern France.

Its origins date back to the 11th century when it was known as "Castrum Sancti Castri," likely referring to a fortified castle built on a rocky promontory.

The commune played a significant role in the Anglo-French rivalry during the Middle Ages and was the site of the Battle of Saint-Cast in 1758, where the British suffered a decisive defeat.

Saint-Cast-le-Guildo is situated on the Emerald Coast (Côte d'Émeraude), known for its breathtaking beaches and dramatic coastline.

It has a population of approximately 3,500 inhabitants, with a modest population growth rate in recent years.

The economy of Saint-Cast-le-Guildo is primarily driven by tourism, agriculture, and fishing.

It is home to the Fort La Latte, a 14th-century castle perched on a rocky headland, classified as a historical monument and a popular tourist attraction.

The commune is also renowned for its traditional Breton culture, including festivals, music, and local cuisine featuring seafood and buckwheat specialties.

Saint-Cast-le-Guildo played a role in the national history of France during World War II, serving as a landing point for Allied troops during the D-Day operations.

It is not associated with any UNESCO World Heritage Sites but has several protected natural areas, such as the Saint-Cast-le-Guildo forest.

The commune hosts an annual "Fête de la Mer" (Sea Festival) in August, celebrating local maritime traditions and culture.

The traditional Breton dance form, "laridé," is particularly popular in Saint-Cast-le-Guildo and is showcased during various cultural events.

The commune is known for its production of high-quality oysters, which are cultivated in the nearby bay.

It has a small but active art community, with local galleries and studios showcasing the work of regional artists.

Saint-Cast-le-Guildo is well-connected by road and rail, making it easily accessible from major cities like Rennes and Saint-Malo.