Morella's castle sits on a rocky pinnacle 1,000 metres above sea level, the highest point of an already elevated old town. It was built by Christian forces in the 13th century following the Reconquista and served as a formidable fortress for centuries. The ruins are substantial and the views from the battlements extend for 50km or more on clear days — south to the coastal plain, north into Aragon, and west into the high plateaux.
The access path from the old town is steep and takes about 20 minutes. Inside, various towers and walls are explorable; the aqueduct that supplied water to the castle from a spring below the town is still visible. Entry is cheap. Allow an hour to explore properly.