The Baroque architecture, in the Italian taste, is attributed to Nicolau Nasoni in view of its similarity of style to other works by him. According to Robert Smith, a specialist in his work, the architect is likely to have spent the years 1739 – 1743 on the construction of the house, or at least on its central façade and decoration.
In addition to the Baroque splendour of the principal façade and the richness of the decorative detail, consisting of curved entablatures, pediments, pinnacles and statuary, the building is impressive for the mathematical precision of its layout and the regularity of its dimensions and their variation.
The overall plan is a rectangle divided into two hollow squares, which create a number of wings and two courtyards interlinked by massive arches at ground level. The front courtyard is open on the fourth side, providing views of the principal façade, while the rear courtyard is closed, creating a central axis of perspective through the massive arches at ground level that pierces the entire building, cutting it in two and forming a harmonious perspective in the classical style.
The principal floor is reached by double staircases which are repeated on the side elevations of the two courtyards, two on the west side and one on the east side, which accentuate the symmetry and Baroque rhythm of the decoration.
On the first floor in the centre of the building, between the courtyards and with façades overlooking both, the Salão de Entrada defines the meeting line of the two squares comprising the plan. The Salão de Entrada provides access northwards to the Library and the wing housing the bedrooms, and south to the Sala do Tijolo and the wing accommodating the reception rooms. The two wings are interconnected at their east end by a wing of bedrooms which gives access to the Choir of the Chapel.
Yellow granite is used in the construction of the double walls and masonry detail, while light chestnut wood is used in the doorcases, the carved plain or domed coffered ceilings and the heraldic pediments over the doors.
References in documents in the Casa’s archives and careful study of the plan and construction elements indicate the existence of possible traces of the original building and different stages in the construction of the Hose. Variations in the nature of the masonry work and in the thicknesses of the walls may point to successive construction stages, with the front wings possibly being more recent, as has been suggested by Vasco Graça Moura in his studies of the Casa.
The architectural complex is completed by the Chapel and the Winery, which contribute to the monumentality of the overall effect, with its harmonious volumes. The front of the Chapel is parallel to the principal façade of the Casa and leads back to the rear façade, creating space for the open court with its Cross which separates the House from the Winery.
Construction of the Chapel was completed in 1750 by D. Luís António de Sousa Botelho Mourão to a design influenced by Nicolau Nasoni and executed by Master José Álvares do Rego. Richly ornamented, the height of the façade echoes that of the principal façade of the Casa.
The Winery buildings date from the 16th century and were incorporated into the House by D. Maria Coelho and her husband in 1655. They were subsequently extended to the west and east (in 1854 and 1856 respectively) to align them with the principal and rear façades of the House. The Winery consists of two longitudinal bodies running parallel to the House, marked by great purity of line broken by pilasters and attractive masonry detail around the first floor windows.
Other agricultural buildings make up the rest of the complex, of which the most important are the so-called ‘Barrão’ (barn and toolstore) and the ‘Eira’ (threshing shed) to the south of the House, next to the fountain that for many years provided the water supply to the House.
D. Luís António and his son D. José Maria de Sousa Botelho Mourão e Vasconcelos left inventories that enable us to understand the functions of the various parts of the House and what they contained. The arrangement of the floors provides an insight into daily life at the end of the 18th and beginning of the 19th centuries, and the arrangement of the north and east wings, the first floor of which differed from that we see today. The central part of the east wing housed six bedrooms and small anterooms, and the north wing, in addition to the Salas de Mateus d’Allem in its front part, also contained a series of small bedrooms with a central corridor, a latrine and access to the attic.