Santa Maria Maggiore in Aventino was a little farmstead chapel on the Aventine, when the district was completely rural. It was about where the Piazza del Tempio di Diana is now.
The Nolli Map of 1748 shows a farmstead or villa to the south-east of Santa Sabina, with a driveway along the present line of Via Raimundo da Capua. Another driveway ran westwards from just north of Santa Prisca. The farm was completely surrounded by vineyards.
The chapel had a transverse rectangular plan with a sem-circular apse, and was at the west end of the main block. The Roman Campagna had several such farmsteads with their own chapels, some of which survive, but this seems to have been the only such establishment within the walls.
In the reign of Pope Leo III, there was a monastery somewhere around hear called San Donato which was described as "near Santa Prisca". It might have been on the site of the farmstead, but any proof would be as a result of a lucky archaeological find.
The usual historical commentators do not seem to have noticed this chapel. The name was either a joke, given the tiny size of the chapel, or the farmstead was owned by the Chapter of Santa Maria Maggiore.
The farmstead, chapel and vineyards all went for suburban development at the end of the 19th century. The site of the chapel is the north-east corner of the Piazza del Tempio di Diana.
Nolli map (item 1078)