Barcelona is a walkable global city known for breathtaking architecture, world-class museums, bustling markets, parks, and fashion. Start at Montjuïc Castle for city views, then visit the Joan Miró and National Art Museum. Spend a day in the Gothic Quarter and Museu Picasso. The city is especially famous for Antoni Gaudí's work, from La Sagrada Família to Park Güell. Along La Rambla, you'll find more architecture, designer shopping, and great tapas.

Valencia blends centuries of architecture: the cathedral began in 1262 and may house the Holy Grail; Plaza del Mercado pairs Mercado Central with the Gothic Lonja de la Seda, a UNESCO silk exchange; the City of Arts and Sciences by Santiago Calatrava opened in 2005; nearby are the Lladró Porcelain Museum, a beachfront promenade, and the city where paella was invented.

Founded by Carthaginians circa 220 BC, Cartagena has one of the world's oldest naval bases and rich Roman archaeology. Highlights include the 1st-century Roman theater, Barrio del Foro Romano, Casa de la Fortuna, and the Punic Wall Interpretation Center. The ARQUA Museum displays finds from off Murcia's coast, and Castillo de la Concepción offers panoramic views. Beyond history, Cartagena has coves, beaches, fine dining, and activities for divers, hikers, golfers, and windsurfers.

Málaga, on the Costa del Sol, blends golden beaches, mild Mediterranean weather and mountain shelter. One of the world's oldest cities, founded 2,800 years ago, it was shaped by Phoenicians, Romans and Moors. Highlights include the Alcazaba, Gibralfaro, 30+ museums, Picasso's museum, Centre Pompidou, lively street art, chic dining and traditional porra antequerana. Nearby white villages add Andalusian charm.

Gibraltar, a British Overseas Territory on Spain's southern coast, is dominated by the Rock of Gibraltar, "The Rock." A six-minute cable car ride offers views of two continents, two bodies of water, and three countries. See the Gibraltar Nature Reserve and its Barbary macaques, St. Michael's Cave, the Great Siege Tunnels, and Gorham's Cave Complex, a UNESCO site with Neanderthal evidence dating back 120,000 years.

Lisbon, Portugal's Atlantic capital, is spread across seven hills. Start in Alfama, with its medieval streets leading to Castelo de São Jorge and sweeping city views. Head to Baixa for shopping, restaurants, and neoclassical architecture. In Belém, see two UNESCO sites: Belém Tower and Jerónimos Monastery. If time allows, visit nearby Sintra and Cascais, or continue to Fátima, where Virgin Mary apparitions were reported in 1917.