It has been classified as a National Monument since 1910. All the studies on the Solar de Mateus are unanimous in considering it one of the most significant works of Portuguese civil architecture from the Baroque period. In reality, and despite the many questions of authorship that remain unclear, what is certain is that this sumptuous manor house contains all the elements that characterise Baroque architecture, namely symmetry, axiality, interrupted pediments, balustrades, staircases and high pinnacles. It is not known for sure when the House began to be built, but it is certain that it was completed in 1744, and the Chapel was finished in 1750, a date that coincides with the time when the Italian architect Nicolau Nasoni worked in the area, to whom the authorship of the work is attributed. This is not, however, a peaceful question since, on the one hand, there is an obvious similarity between this building and the architect's other works, on the other hand, there are those who believe that the profusion of decoration on the façade of Mateus and the use of various architectural elements are completely foreign to Nasoni and may have been executed later. Today, the Casa de Mateus is administered by the Foundation of the same name, founded on 3 December 1970 and run by the family, organising various cultural activities, as well as preserving the library and museum.