Castillo de San Gabriel Arrecife

On a little islet just off the seafront promenade, reached via the 18th-century Puente de las Bolas or a more recent Franco-era bridge, the 16th-century Castillo de San Gabriel was originally built to fend off pirate attacks. Today it holds the Museo de Historia de Arrecife, with Spanish-language exhibits on the island's geology, flora and fauna as well as pre-Hispanic life, the Spanish conquest and the capital's history. Climb to the battlements for sweeping views across Arrecife.