Building Southern Europe as the World's Biofuels and SAF Hub examines one of global aviation decarbonization's most consequential geographic opportunities. Beyond cataloguing projects, this report analyzes the structural forces that make Southern Europe uniquely positioned to lead — from Mediterranean feedstock endowments and record-low renewable energy costs to world-first biorefinery conversions and Atlantic-Mediterranean port logistics. It maps 56 SAF projects across Spain, Portugal, France, and Italy, profiling the flagship investments, technology pathways, and company strategies driving capacity from ambition to operation. With biofuels as the proven industrial foundation and SAF as the core growth engine, Southern Europe is not waiting for the energy transition — it is building it. This whitepaper provides a strategic lens on why the region is set to become the world's sustainable aviation fuel powerhouse.