Alderdi Eder Park

This guide to Alderdi Eder Park in San Sebastián opens with Mata Hari watching the lights of a casino ballroom from a nearby hotel window in the 1910s, drawn to the powerful men gambling inside. Spain's neutrality in the First World War turned this seaside park into a quiet meeting ground for diplomats, exiled royals and spies trading rumors between hands of cards. You'll hear how the golden-domed casino, opened in 1887 to lure Spanish high society away from Biarritz, later lost its purpose when a 1924 decree outlawed gambling nationwide. Walk the lawns beneath the century-old tamarisk trees a French gardener once planted here.