Guillestre is a historic commune in the Hautes-Alpes department of the Provence-Alpes-Côte-d'Azur region in southeastern France.

Founded by the Romans as "Ad Fines," Guillestre strategically guarded the passage between Dauphiné and Piedmont and served as the capital of the Guillestrois region.

Destroyed by fire in the 8th century, Guillestre was rebuilt and fortified in the 11th century and became a prosperous trading center.

The town played a crucial role in the French Wars of Religion and was besieged several times by Protestant and Catholic forces.

Guillestre is situated in the Durance River valley at the confluence of the Guil and Durance rivers, surrounded by the Cottian Alps.

As of 2023, Guillestre has a population of approximately 2,300, experiencing a slight increase in recent years.

The local economy is primarily driven by tourism, agriculture, and small businesses.

Guillestre is known for its well-preserved medieval architecture, including the 12th-century fortified church of Notre-Dame, the ancient clock tower, and the Porte de France.

The town also boasts several museums, including the Eco-Museum of the Guillestrois, showcasing the region's cultural heritage.

Guillestre is a gateway to the Queyras Regional Nature Park and the Serre-Ponçon Lake, offering ample opportunities for outdoor activities such as hiking, biking, and water sports.

The annual "Guillestrois en Fête" festival celebrates the town's history and culture with parades, concerts, and traditional crafts demonstrations.

Guillestre has a strong tradition of mountain biking and is home to the popular "Dolomiti Superbike" event, attracting cyclists from around the world.

The town has produced notable figures throughout history, including the 19th-century author and mountaineer Henry Duhamel and the 20th-century politician Jean Giono.

Guillestre has no UNESCO World Heritage sites within its boundaries but lies in proximity to several, including the Vauban fortifications of Mont-Dauphin.

The commune is actively involved in environmental conservation efforts and is part of the "Coeur de Parc" network of municipalities committed to sustainable development in protected areas.