3 Best Sights in Catalonia, Valencia, and the Costa Blanca, Spain

One of the largest existing medieval fortresses in Europe, Castillo de Santa Bárbara sits atop 545-foot-tall Monte Benacantil. From this strategic position you can gaze out over the city, the sea, and the whole Alicante plain for many miles. Remains from civilizations dating from the Bronze Age onward have been found here; the oldest parts of the castle, at the highest level, are from the 9th through 13th centuries.

The castle also houses the Museo de la Ciudad de Alicante (MUSA), which uses audiovisual presentations and archaeological finds to tell the story of Alicante, its people, and the city's enduring relationship with the sea.

Just a minute's drive northwest of Figueres is this imposing 18th-century fortified castle, one of the largest in Europe—only when you start exploring can you appreciate how immense it is. The parade grounds extend for acres, and the arcaded stables can hold more than 500 horses; the perimeter is roughly 4 km (2½ miles around). This castle was the site of the last official meeting of the Republican parliament (on February 1, 1939) before it surrendered to Franco's forces. Ironically, it was here that Lieutenant Colonel Antonio Tejero was imprisoned after his failed 1981 coup d'état in Madrid.

Call ahead and arrange for the two-hour Catedral de l'Aiguas guided tour in English (€15), which includes a trip through the castle's subterranean water system by Zodiac pontoon boat.

The most interesting architectural attraction here is the castle overlooking the town, and the Palau del Governador (Governor's Palace) inside. On the site of an 11th-century Moorish fortress, the Renaissance-era palace was built in the 17th century and was later demolished. The fortress has an interesting archaeological museum as well as the remains of a Renaissance bastion and a Moorish portal with a lovely horseshoe arch.