The chapel is entered from the nave by a large arch enriched in front with beautiful cherubs' heads and wreaths of flowers, and on the under side with coffered panels. This arch springs from a beautifully modelled entablature borne on either side by a Corinthian pilaster, panelled and carved, and by a column fluted above, and wreathed with hanging fruits and flowers below, while similar arches form recesses on the three remaining sides of the chapel, one--to the north--containing the altar, and the other two the tombs of Diogo and of Lourenço da Silva.
On the nave side, outside the columns, there stands on either side--placed like the columns on a high pedestal--a pilaster, panelled and carved with exquisite arabesques. These pilasters have no capitals, but instead well-moulded corbels, carved with griffin heads, uphold the entablature, and, by a happy innovation, on the projection thus formed are pedestals bearing short Corinthian columns. These support the main entablature whose cornice and frieze are enriched, the one with egg and tongue and with dentils, and the other with strapwork and with leaves. In the spandrils above the arch are medallions surrounding the heads of St. Peter and of St. Paul, St. Peter being especially expressive.
Inside, the background of each tomb recess is covered with strapwork, surrounding in one case an open and in another a blank window, but unfortunately the reredos representing the Visit of the Magi is gone, and its place taken by a very poor picture of Our Lady of Lourdes.
The pendentives with their cherub heads are carried by corbels in the corners, and the dome is divided by bold ribs, themselves enriched with carving, into panels filled with strapwork. (Fig. 80.)
This chapel then is of great interest, not only because of the real beauty of its details but also because it was the first built of a type which was repeated more than once elsewhere, as, for instance, at Marceana near Alemquer, on the Tagus, and in the church of Nossa Senhora dos Anjos at Montemor-o-Velho, not far from São Marcos. Of the chapels at Montemor one at least was built by the same family, and in another where the reredos--a very fine piece of carving--represents a Pietà, small angels are seen to weep as they look from openings high up at the sides.