Catedral de Avila: One of the earliest Gothic cathedrals in Castile, this rugged, plain edifice was called "a soldier's church." A brooding, granite monolith, which in some ways resembles a fortress, it is the centerpiece of a city that produced St. Teresa, the most famous mystic of the Middle Ages. The interior of the cathedral, with its High Gothic nave, is filled with notable works of art, including many Plateresque statues.
Catedral de Toledo: Ranked among the greatest of all Gothic structures, this cathedral was built on the site of an old Arab mosque. A vast pile from the 13th to the 15th centuries, it has an interior filled with masterpieces -- notably an immense polychrome retable carved in flamboyant Gothic style, and magnificent 15th- and 16th-century choir stalls. In the treasury is a splendid 16th-century silver-and-gilt monstrance, weighing about 500 pounds.
Real Monasterio de San Lorenzo de El Escorial (near Madrid): Philip II, who commissioned this monastery in the 1530s, envisioned it as a monastic fortress against the distractions of the secular world. More awesome than beautiful, it's the world's best example of the religious devotion of Renaissance Spain. This huge granite fortress, the burial place for Spanish kings, houses a wealth of paintings and tapestries -- works by everyone from Titian to Velázquez.
Catedral de León: Filled with more sunlight than any other cathedral in Spain, this one was begun in 1250 with a design pierced by 125 stained-glass windows and 57 oculi, the oldest of which date from the 13th century. The architectural achievement is stunning but also dangerous: Architects fear that an urgent restoration is needed to strengthen the walls to prevent collapse. The well-preserved cloisters are also worth a visit.
Catedral de Santa María (Burgos): After its cornerstone was laid in 1221, this cathedral became the beneficiary of creative talent imported from England, Germany, and France. It is the third-largest cathedral in Spain, after Seville and Toledo. Art historians claim that among medieval religious buildings, it has the most diverse spectrum of sculpture in Gothic Spain -- so diverse that a special name has been conjured up to describe it: the School of Burgos. El Cid is buried here.
Catedral de Sevilla: The Christians are not the only occupants of Seville who considered this site holy; an enormous mosque stood here before the Reconquest. To quote the Christians who built the cathedral, they planned one "so immense that everyone, on beholding it, will take us for madmen." They succeeded. After St. Peter's in Rome and St. Paul's in London, the cathedral of this Andalusian capital is the largest in Europe. Among its most important features are the tomb of Columbus, Patio de los Naranjos (Courtyard of the Orange Trees), Giralda Tower, and Capilla Real (Royal Chapel).
Mezquita-Catedral de Córdoba: In the 1500s, the Christian rulers of Spain tried to convert one of the largest and most elaborate mosques in the Muslim world, the Mezquita, into a Catholic cathedral. The result, a bizarre amalgam of Gothic and Muslim architecture, is an awesomely proportioned cultural compromise that defies categorization. In its 8th-century heyday, the Mezquita was the crowning Muslim architectural achievement in the West.
Catedral de Barcelona: Completed in 1450, this cathedral grew to represent the spiritual power of the Catalan empire. With its 81m (266-ft.) facade and flying buttresses and gargoyles, it is the Gothic Quarter's most stunning monument. The interior is in the Catalan Gothic style with slender pillars.
Montserrat (near Barcelona): Since its inauguration in the 9th century by Benedictine monks, Montserrat has been the preeminent religious shrine of Catalonia and the site of the legendary statue of La Moreneta (the Black Madonna). Its glory years ended in 1812, when it was sacked by the armies of Napoleon. Today, sitting atop a 1,200m (3,936-ft.) mountain, 11km (7 miles) long and 5.5km (3 1/2 miles) wide, it is one of the three most important pilgrimage sites in Spain.
Museo Catedralicio de Santiago de Compostela: During the Middle Ages, this verdant city on the northwestern tip of Iberia attracted thousands of religious pilgrims who walked from as far away as Italy to seek salvation at the tomb of St. James. The cathedral itself shows the architectural influences of nearly 800 years of religious conviction, much of it financed by donations from exhausted pilgrims. Its two most stunning features are its Obradoiro facade (a baroque masterpiece) and its carved Doorway of Glory behind the facade. An enormous silver censor, called the Botafumeiro, swings from the transept during major liturgical ceremonies.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.