Hagios Ioannis Mangoutis is one of the oldest churches in Athens. It was a small, three-aisled, timber roofed basilica, which was demolished in 1850. It was situated on the northern slope of the Acropolis, on today’s Erechtheos Street in Plaka, close to the post Byzantine church of Hagioi Anargyroi Kolokynthi (Metochion of the Holy Sepulcre). It was built in 871 and the owner’s inscription with the foundation date has been preserved.
Panselinou N., Byzantine Athens, Athens 2004, p.49.