Santa Maria Imperatrice was a small 17th century devotional church, which was demolished and rebuilt on a slightly different site in the 19th century. It was at the east end of Via dei Santi Quattro, in the rione Campitelli.
The dedication was to the Blessed Virgin Mary as Empress of Heaven and Earth.
The site of this church has been claimed as being that of the ancient lost church of San Gregorio in Martio, but this is disputed.
The reason for its foundation was the devotion being paid at the end of the 16th century to a fresco icon of the Madonna and Child, which was in a roadside shrine or sacello outside the entrance to the convent of Santi Quattro Coronati. The church was built in 1606, and the image transferred to it.
A tradition had become established that it dated back to the 6th century, and that it had spoken to Pope Gregory the Great. As a result, in the reign of Pope Alexander VII (1655-67) it was enshrined behind an iron grille over the altar, and an inscription added recording the tradition.
In 1826, the image was transferred to the nearby new chapel of Santa Maria delle Grazie nel Cimitero in Laterano; according to an inscription placed on its façade, this was because the old chapel was in bad repair. The owner of the adjacent garden, the Giardino Campana, rebuilt the chapel in the middle of his garden as a private act of devotion. This in turn was demolished in the late 1880's, when the garden was sold and the present apartment blocks built.
The original location was on the north side of the Via dei Santi Quattro, just west of the junction with the Via Santo Stefano Rotondo. The 17th century church was set longitudinally to the street at a slight angle. Hence, there was a tiny triangular piazza there.
The site is now a row of apartment buildings butted together on the north side of the street, and the chapel was about where there is a vertical line of long-and-short blocks marking where two buildings join together.
The site of the rebuilt 19th century chapel is occupied by the block to the right of this feature.
The orientation was from north-west to south-east, with the entrance to the far left of the street frontage (which was the right hand side wall). Four pilasters supported the ceiling vault; the floorplan was a simple rectangle.