A hidden gem within the Costa Southern Charms, Bolonia beach is famous for its 1,000-year-old sand dune—one of the largest and best-preserved mobile dune systems in Europe. It encroaches slowly on the Roman ruins of Baelo Claudia , one of the best-preserved ancient Roman towns in Spain. Walking through the forum of a 2,000-year-old city while a 30-meter dune looms behind you is an experience unmatched anywhere else on the continent.