The document summarizes four UNESCO World Heritage Sites located in Spain and Romania: 1) The Dacian Fortresses of the Orastie Mountains in Romania, which show the fusion of military and religious architecture from the classical world and late Iron Age in six well-preserved fortresses that were once part of the Dacian Kingdom. 2) The Danube Delta in Romania, which forms the largest and best preserved river delta in Europe and is home to over 300 bird species and 45 freshwater fish species. 3) Las Medulas in Spain, where the Romans exploited gold deposits through hydraulic mining techniques until abandoning the area two centuries later, leaving dramatic traces of the ancient technology visible