The San Antón Bridge (Spanish: Puente de San Antón, Basque: San Antongo zubia) is an arch bridge in Bilbao, Spain. It spans the Estuary of Bilbao, linking the neighborhoods of Bilbao La Vieja and Casco Viejo. It is the oldest bridge in the city, with the original bridge being opened before 1318. At the time of its opening, and during centuries, it was the only bridge that crossed the river.