SANTANDER
The tower is the Torre del Oro (Golden Tower) of Seville, and the broken chains and galleon refer to the very important participation of the Santanderns ships in an ancient battle in the 13th century, where a great army of Castille went upstream the Guadalquivir river, and broke the muslims resistance to reconquest Seville. The muslims put large chains across the river to avoid the Castillian vessels to pass, but the chains were broken and the Santander ships where the first to pass.
The two heads are from two saints, St. Emeterio and St. Celedonio, the patron saints of the city. Their heads were cut off hence only the heads are commonly shown.
Literature : de Cadenas, A. A. and de Cadenas, V. : Heraldica de las comunidades autonomas y de las capitales de provincia. Hidalguia, Madrid, 1985. Background provided by Rafael Lastra, Spain
coats of arms on-line ! 
