It used to be in the angle of the city wall just west of the present Via del Perugino, and was accessed via an alleyway from the Piazza Santa Marta called the Vicolo dello Scalone.
The Nolli map of 1748 shows it as a single-roomed rectangular edifice between two gardens laid out against the city walls. The garden to the west survives, behind the Palazzo San Carlo. A wing of this building now stands over the site of the chapel.
It was still standing at the end of the 19th century, and presumably went during the re-ordering of the area in the 1920's.