Ibiza pro­vides an excel­lent exam­ple of the inter­ac­tion between the marine and coastal ecosys­tems. The dense prairies of ocean­ic Posi­do­nia (sea­grass), an impor­tant endem­ic species found only in the Mediter­ranean basin, con­tain and sup­port a diver­si­ty of marine life. Ibiza pre­serves con­sid­er­able evi­dence of its long his­to­ry. The archae­o­log­i­cal sites at Sa Cale­ta (set­tle­ment) and Puig des Molins (necrop­o­lis) tes­ti­fy to the impor­tant role played by the island in the Mediter­ranean econ­o­my in pro­to­his­to­ry, par­tic­u­lar­ly dur­ing the Phoeni­­cian-Carthag­in­ian peri­od. The for­ti­fied Upper Town (Alta Vila) is an out­stand­ing exam­ple of Renais­sance mil­i­tary archi­tec­ture, it had a pro­found influ­ence on the devel­op­ment of for­ti­fi­ca­tions in the Span­ish set­tle­ments of the New World.