Château d'Abbadia is a distinctive castle-observatory built between 1864 and 1884 on the Basque coast in Hendaye, designed by renowned architect Viollet-le-Duc. Constructed for Antoine d'Abbadie, an accomplished ethnologist, geographer, and man of science who served as cultural patron for the Basque region, the château features distinctive neogothic architecture and eclectic decoration. Positioned dramatically on coastal cliffs, the monument functions as both a museum and heritage destination. Guided tours operate daily during summer months with mandatory reservations, while unguided visits offer flexible exploration of this significant cultural landmark.