Madonna dell'Archetto
Italy
The Church of the Madonna dell'Archetto (English: Our Lady of the Little Arch) is a small oratory in Rome, Italy, in the Trevi rione. The official title of the church is Santa Maria Causa Nostrae Laetitiae (English: Holy Mary, Cause of Our Joy). It is often cited as being the smallest church in Rome.
Data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).