The oven ‘O Forno’, from which Sta. Mariña was miraculously rescued by St. Peter, is located in an open field on the perimeter of the Armeá castro and is believed to be a Christianized castro sanctuary with its large ‘Pedra Formosa’ adorned with a serpent. In the 14th century, a lady from the House of Figueroa ordered the construction of a church on top, known as the Basilica of the Assumption. It was never completed, but its walls show what would have been a simple single-nave church over a crypt with a pointed vault. In the crypt, there are medieval sepulchral slabs, some of Visigothic tradition.