1. From Entre-os-Rios, the N222 heads high above the south bank of the Douro, before hugging the water as far as pretty Pinhão.
2. Drive across the highest mountains in Portugal, from Seia to Covilhã on the N339.
3. The trans-Trás-os-Montes N103 snakes around northern Portugal’s wildest terrain, skirting the Parque Natural de Montesinho.
4. The vertiginous N379-1 crosses the Serra de Arrábida mountains high above the Baia de Setúbal, providing stunning coastal views.
5. The N265 from Serpa to Mértola is a bucolic back-route through the Alentejo’s stunning Parque Natural do Vale do Guardiana.