The dedication was to St John the Baptist.
The church was founded in the early Middle Ages as San Giovanni della Ficozza, and was named after a local noble family. However, the date and circumstances of the foundation are unknown and the first documentary reference to it dates to 1199. Back then, it was dependent on the church of San Marcello al Corso but became parochial in the later Middle Ages. Members of the family are on record in donating money for renovations in 1224 and 1409.
A college for clergy of the Maronite rite was founded in an adjacent house in 1584, and the church was granted to it. Hence, it became the national church of the Maronites in Rome; the parish was united with that of Sant'Andrea delle Fratte. There was a restoration in 1700.
The complex was damaged during the French occupation firstly in 1798, and then plundered by French soldiers in 1808. It was re-consecrated in 1846, but the monastery was again suppressed with all others in the city by the new Italian government in 1873.
The Collegio Polacco, for Polish (and initially Slovenian) seminarians from the Hapsburg Empire, was founded in 1866, and initially occupied a house on the Via della Salara Vecchia in the Roman Forum, behind the present Curia. This institution took over the old Maronite complex from the government in 1878. A new church and monastery, San Marone, were eventually built for the Maronites in the Villa Ludovisi development from 1889 to 1914 with the church being finished in 1902.
The dedication was changed in this period of use by the Poles, to San Giovanni Canzio. This was in honour of St John of Kenty, a professor at the University of Cracow in Poland. The Polish College remained here until 1936, when it was decided that the premises were too cramped and dilapidated for further use. So, the college moved to Piazza Remuria on the Little Aventine in that year, where it remains.
The complex was secularized once again, and the church was used firsly as a garage, and then as a bar. Since 1998, it has housed a trattoria known as Sacro e Profano ("Sacred and Profane"). The original layout of the church is preserved, and many frescoes remain -which are easily examined through having a meal here.
The church was on a rectangular plan, with a separate transverse rectangular presbyterium entered through a triumphal arch. There was no architectural identity separate from that of the college to the east.
There is no proper façade. The only two things of note are: A gigantic pilaster occupying the street corner on the right, with a Doric capital in the form of an inverted plinth, and a large window with a Baroque frame above the entrance. There used to be a stucco relief of Our Lady over the entrance, dating from the 15th century.
There used to be two side chapels. The one on the right was dedicated to Our Lady, and had a statue of her by Czosnowsky. The one on the left had a sculpture of the Ecce Homo by the same artist. The main altarpiece was a 19th century Polish work depicting Our Lady with SS John of Kenty, Stanislaus, Adalbert of Prague and Casimir.
Inside, the rather naïve frescoes survive on the flat wooden ceiling, above the triumphal arch, on the left hand wall and on the far wall of the presbyterium. Two frescoed figures also decorate the the otherwise unembellished arch in shallow relief which encloses the entrance and window in the counterfaçade. There used to be a side entrance to the nave, and this blocked entrance is enclosed by an arch of similar design.
Excavations have revealed ancient Roman remains beneath the building.