For centuries, the lost civilisation of Tartessos -- which emerged in the Iberian peninsular almost 3,000 years ago -- was shrouded in mystery, but today its secrets are slowly being revealed through the meticulous work of archaeologists. "We still don't know where or why they left", says Esther Rodriguez, in charge of the Casas del Turunuelo site, where excavation work has been ongoing since 2015.