Rafael dP from España, CC BY-SA 2.0 , via Wikimedia Commons
Capital of western Spain's Extremadura region with impressive Roman ruins on the UNESCO list. It was founded by the Romans in the 1st century B.C. Remains of the ancient city include the still-used Teatro Romano, which has a double tier of columns rising onstage. The ancient Puente Romano, a 792m bridge spanning the Río Guadiana, adjoins the Alcazaba, a 9th-century Islamic fortress built over Roman walls.