Castle of Alter do Chão

Alter do Chão Castle (Castelo de Alter do Chão) is a medieval fortress in the Alentejo region of Portugal, in the Portalegre District. It stands in the centre of the small town of Alter do Chão and has been classified as a National Monument since 1910. It is a worthwhile stop for anyone interested in the history of the Portuguese-Castilian frontier.

What does Alter do Chão Castle look like?

The present building is a good example of 14th-century defensive architecture. It follows a square plan, and its walls are reinforced by six towers, four of them at the corners. The layout is compact and easy to read, typical of Portuguese castles of the period, where military function mattered more than display.

When was the castle built?

The first fortress on the site is thought to date from the Muslim period, probably the first half of the 10th century, under Abd al-Rahman III. After Afonso II conquered the settlement, Christian resettlement of the village was ordered.

The current castle is the result of a reconstruction under King Peter I, carried out in 1359. At that time, fortifications in the region were built not against the Moors but because of the threat from neighbouring Castile, to the east.

Why does it matter in Portuguese history?

King John I broke an earlier commitment made by King Denis and gave military command of the town to Nuno Álvares Pereira, a renowned commander. His daughter inherited the castle and town, and through her marriage they passed to the House of Braganza, one of the most important noble families in Portugal.

What should you know before visiting?

• The castle is in the town itself, so it is easy to combine with a walk through the surrounding streets.
• Its coordinates are roughly 39.199 N, 7.659 W.
• Check current opening hours and rules for visiting the interior before you go, as they may change.
• Alentejo has many other monuments and small towns that fit well into a day trip.

Frequently asked questions

Where is Alter do Chão Castle? In the town of Alter do Chão, in the Alentejo region, Portalegre District, Portugal.

Which period is the present castle from? The 14th century. It was rebuilt in 1359 under Peter I.

What is its layout? A square plan with six towers, four of which stand at the corners.

Is it a protected monument? Yes, it has been a National Monument of Portugal since 1910.

What was it meant to defend against? Not the Moors, but the threat from Castile to the east.