With a single stroke, which is thought to be the Custos Vieira architect, the temple is an example of the palatine architecture located at the eastern end of the Palace of Passagens.

Its main façade has a small niche with a San Antonio image that is believed to have been brought from the old Chapel of S. Fernando / S. António do Outeiro. Inside, it is composed of a single nave, altar, baptistery, real oratory and the sacristy.

It is noteworthy also the background of the main altar covered with a barrel vault, with paintings done in the style of John V, which are represented perhaps the four evangelists, surrounded by wreaths and medallions with some Latin couplets.

The continuous paneling of blue and white tiles all around the chapel, with about 1.80 m high, is made up of different figurative panels, which can be dated to 1750, but one with the image of Santa Barbara, patron saint artillery, dating from 1972.

On the altar there are two images, one of Our Lady of Conception in upholstered wood, end of the century. XVII and other Santa Barbara, brought on crossing the chapel to the Army field.

Near the sacristy lies the Oratory Real, where royals attended Mass, and other storage rooms.

The chapel was from 1843 to 1969 church of New Sales and currently despite belonging to the Artillery School in it are performed weddings and Mass occasionally.