To the right of the Puerta de la Gracia, standing against the medieval wall, it was decided to erect the Casas da Câmara (Town Hall) in the mid-15th century. Also known as the Palacio de los Duques de Cadaval, which has survived to the present day, its name is misleading. In fact, this building was never the palace of the Dukes of Cadaval, owing its name to the fact that they were once the regional magistrates of Olivenza.
Its facade is composed of two levels. On the lower level there are two large arches: the main door in Manueline style and another to the right, which is voussoired. On the left side, next to the Puerta de la Gracia, there is an old access door to the upper level with its typical marble framework. Above it, a marble tablet features the Portuguese coat of arms flanked by an armillary sphere, symbolising conquests overseas, and the coat of arms of Olivenza. The elements of the Portuguese national coat of arms were removed to dedicate the tablet to Queen Isabel II. An inscription was later re-engraved in its place, to celebrate the Spanish constitution of 1845.
On the upper level, there are windows with railings and a balcony where the flags of Europe, Spain, Extremadura and Olivenza fly.
The unique Manueline arch door has become the identifying symbol of the city. Here, we can see the characteristic elements of the national style of Portugal, which owes its name to King Manuel I the Fortunate: the profuse decoration of the intrados using various plant motifs; the Arabic influenced polylobed arch; the Armillary Spheres, the emblem of King Manuel and the symbol of the overseas conquests; and the Cross of Christ at the top. In the central motif, we can see the Portuguese coat of arms, surrounding the tower and the olive tree, the coat of arms of Olivenza.
It is possible that this door was originally at the main entrance of the neighbouring Church of La Magdalena, but this has yet to be scientifically proven.
Divided into two levels, it does not present any noteworthy elements. In the current Plenary Hall, we can see the medieval wall behind it and a vault simulating ribs, made of common construction materials, as well as its keystones decorated with the coat of arms of Portugal, Olivenza and another one yet to be determined.