Soaring 412m above sea level, this mist-enshrouded ruined castle is a Great Wall of China in miniature. Like a dragon’s backbone, this 9th-century Moorish castle’s dizzying ramparts wriggle across the mountain ridges and past moss-clad boulders the size of small buses. When the clouds peel away, the vistas over Sintra’s palace-dotted hill and dale to the glittering Atlantic are – like the climb – breathtaking.