What to see in Spain: 9 must-sees

Step inside the world's most spectacular Nasrid fortress, where fountains, gardens and Islamic architecture compose a haven of astonishing beauty built by the sultans of Granada (1238-1492) as a refuge from the summer heat and a testament to their power. Declared a UNESCO World Heritage Site in 1984, the Alhambra covers 14 hectares where the Comares Palace with its Hall of the Kings (28 carved wooden figures), the Court of the Lions with its 124 marble columns and the Generalife with its fountains and gardens create a labyrinth of beauty that has fascinated writers, artists and travelers for 700 years.

Step inside the mosque where 856 columns of marble, jasper and agate create a seemingly endless forest of stone, a monument to religious tolerance where the 16th-century Christian cathedral rises at its center as a hymn to coexistence between cultures. The Mosque-Cathedral of Córdoba, declared a UNESCO World Heritage Site in 1984, was built between 784 and 987 by the Umayyad emirs and is the largest Islamic building in Western Europe.

Visit Toledo, the city where Christians, Jews and Muslims lived side by side for 500 years, and wander its cobbled alleys to the Gothic Cathedral, the Synagogue of El Tránsito (1357) and the Mosque of Cristo de la Luz (999). Declared a UNESCO World Heritage Site in 1986, this Castilla-La Mancha city preserves in every neighborhood the testimony of three cultures that shared streets, workshops and synagogues. Climb up to the Mirador del Valle viewpoint to see the town tucked into the bend of the Tagus before getting lost in the Jewish quarter.

Behold the unfinished cathedral that Antoni Gaudí designed in 1882 and that Catalans are still building today with tourists' money, a monument to the patience and vision of a genius who devoted 43 years of his life to a work he would never see finished. The Sagrada Família, declared a UNESCO World Heritage Site in 2005, is Spain's most visited church, with 4.5 million tickets a year and a façade that tells the life of Christ in stone, as if Gaudí had wanted to create a stone Bible that the faithful could read with their eyes.

the 500,000 hectares of marshes, dunes and lagoons that make Doñana the most important bird park in Western Europe, a UNESCO World Heritage Site since 1994. Follow its trails through pine woods and scrubland as you watch flamingos turning the wetlands pink, ospreys soaring over the lagoons and, with luck, the silhouette of an Iberian lynx. The landscape changes with every season: in winter thousands of migratory birds arrive, and in spring the water level reveals new corners. Book a guided tour to access the restricted areas.

Stroll beneath Salamanca's golden stone, where the university founded in 1218 still fills classrooms and squares eight centuries on. Look for the famous frog carved into the Plateresque façade, cross the Patio de Escuelas and step into the library that houses medieval codices. In the afternoon the terraces of the Plaza Mayor fill with students, and coffee costs the same as it did in Unamuno's day — you can visit his house next to the cloister. When night falls, the New Cathedral lights up and the alleyways echo with tunas and guitars, a reminder of why this city remains a byword for learning.