The history of Santoña has always been linked to the sea, to such an extent that it is the Cantabrian's major canning port. Its industry is based above all on the commercialization of tuna and its famous anchovies in olive oil. Santoña is divided into two areas: the town centre, which sits on a plain, and a mountainous area on the slopes of El Brusco and El Buciero. The history of the town is linked to the Monastery of Santa María del Puerto, which later gave rise to the Romanesque church of Santa María del Puerto. It was built between the 13th and 17th centuries and houses a reredos of San Bartolomé with Flemish paintings from the 15th century. Equally significant are its military fortifications, grouped around the mountain of Buciero, which is evidence of the strategic importance of the port. Still in good condition are the forts of San Martín, San Carlos and Mazo or Napoleon.