On a rocky hill on the border between Mertola and Castro Verde sits a small chapel called Nossa Senhora de Aracelis (Our Lady of Aracelis). The name Aracelis comes from the Latin ara coeli, meaning "altar of heaven."The chapel itself was built in the 16th century, but the site was used as a lookout by Romans and Moors long before that.

The view is absolutely amazing and it is said that you can see another six chapels from there as far away as Loulé in the Algarve. The chapel is usually closed, but during the last weekend of August there is an annual pilgrimage to the site. An image of Our Lady of Aracelis is carried around the hill, a tradition that is said to bring good news for the coming crops.