Santo Stefano alla Marcigliana is a ruined mediaeval church in a field south of the Via Valle dei Corsi on the city boundary, in the Marcigliana zone.
The dedication was to St Stephen the Protomartyr.
The nearest place with a postal address is Via Valle dei Corsi 128 (not actually in Rome, but in the town of Tor Lupara, since the city boundary runs down the middle of the road). Opposite this house is a long, straight farm drive with a gate. The remains of the church are a little clump of bushes off in the distance, to the left of the line of the drive.
The church finds its first mention in 1547, when it featured on a map drawn by Eufrosino della Volpaia.
There seems to be no documented history.
A semi-circular apse in red brick is all that survives. It is surrounded by a ploughed field.