Surrounded by impressive star-shaped walls, this fortified town was once one of Portugal’s main strongholds. Due to its location near the Spanish border, Almeida has faced frequent sieges through the centuries, yet the town has managed to keep its unique walls in fair condition.

The striking defensive barrier was built during the 17th century and is a fine example of a bastion fort, which at the time were popping up throughout Europe as the use of cannons became more common. It consists of a complex system of bulwarks, ravelins, platforms, trenches, and a moat. There are only two possible entrances, both of which are large, bomb-proof double gates that are accessible through bridges.

The defense system is complete with casemates, sentry-boxes, hidden passages, and embrasures for cannons, which are still present in some sites of the fortress. Though the fortified town’s sharp, geometric splendor is best appreciated from the air, it’s still fascinating to explore the ancient village nestled within its walls.

A primitive, medieval castle was built here during the Moorish occupation of the Iberian Peninsula. The town’s name is derived from al-Ma’ida, the Arabic word for “the table,” which reflects its location atop a plateau. The castle has since had its structure fundamentally changed as centuries passed—it’s been amplified, taken down, and rebuilt as the town of Almeida was successively conquered and reconquered.

Even though the star-shaped walls may seem impenetrable, they haven’t always been able to protect the town within. The castle exploded during the Siege of Almeida in 1810 after a stray shell ignited its main stock of gunpowder. Some of its granite blocks are said to have been found as far as three miles away from their original location. It’s still possible to see remnants of the castle’s foundations inside the town’s star-shaped walls, as well in the lines of displaced stones within the moat. No wall, no matter how long, tall, or geometrically dazzling, is truly impenetrable.